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<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width"> <meta name="nodejs.org:node-version" content="v16.20.0"> <title>Console | Node.js v16.20.0 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/console.html"> <script async defer src="assets/api.js" type="text/javascript"></script> </head> <body class="alt apidoc" id="api-section-console"> <div id="content" class="clearfix"> <div 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 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</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="console" class="interior"> <header class="header"> <div class="header-container"> <h1>Node.js v16.20.0 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" 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href="#new-consoleoptions"><code>new Console(options)</code></a></li> <li><a href="#consoleassertvalue-message"><code>console.assert(value[, ...message])</code></a></li> <li><a href="#consoleclear"><code>console.clear()</code></a></li> <li><a href="#consolecountlabel"><code>console.count([label])</code></a></li> <li><a href="#consolecountresetlabel"><code>console.countReset([label])</code></a></li> <li><a href="#consoledebugdata-args"><code>console.debug(data[, ...args])</code></a></li> <li><a href="#consoledirobj-options"><code>console.dir(obj[, options])</code></a></li> <li><a href="#consoledirxmldata"><code>console.dirxml(...data)</code></a></li> <li><a href="#consoleerrordata-args"><code>console.error([data][, ...args])</code></a></li> <li><a href="#consolegrouplabel"><code>console.group([...label])</code></a></li> <li><a href="#consolegroupcollapsed"><code>console.groupCollapsed()</code></a></li> <li><a href="#consolegroupend"><code>console.groupEnd()</code></a></li> <li><a href="#consoleinfodata-args"><code>console.info([data][, ...args])</code></a></li> <li><a href="#consolelogdata-args"><code>console.log([data][, ...args])</code></a></li> <li><a href="#consoletabletabulardata-properties"><code>console.table(tabularData[, properties])</code></a></li> <li><a href="#consoletimelabel"><code>console.time([label])</code></a></li> <li><a href="#consoletimeendlabel"><code>console.timeEnd([label])</code></a></li> <li><a href="#consoletimeloglabel-data"><code>console.timeLog([label][, ...data])</code></a></li> <li><a href="#consoletracemessage-args"><code>console.trace([message][, ...args])</code></a></li> <li><a href="#consolewarndata-args"><code>console.warn([data][, ...args])</code></a></li> </ul> </li> <li><a href="#inspector-only-methods">Inspector only methods</a> <ul> <li><a href="#consoleprofilelabel"><code>console.profile([label])</code></a></li> <li><a href="#consoleprofileendlabel"><code>console.profileEnd([label])</code></a></li> <li><a href="#consoletimestamplabel"><code>console.timeStamp([label])</code></a></li> </ul> </li> </ul> </li> </ul></div></div> </li> <li class="picker-header"> <a href="#"> <span class="collapsed-arrow">►</span><span class="expanded-arrow">▼</span> Index </a> <div class="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">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 active">Console</a></li> <li><a href="corepack.html" class="nav-corepack">Corepack</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="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="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" 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<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="#"> <span class="collapsed-arrow">►</span><span class="expanded-arrow">▼</span> Other versions </a> <div class="picker"><ol id="alt-docs"><li><a href="https://nodejs.org/docs/latest-v19.x/api/console.html">19.x</a></li> <li><a href="https://nodejs.org/docs/latest-v18.x/api/console.html">18.x <b>LTS</b></a></li> <li><a href="https://nodejs.org/docs/latest-v17.x/api/console.html">17.x</a></li> <li><a href="https://nodejs.org/docs/latest-v16.x/api/console.html">16.x <b>LTS</b></a></li> <li><a href="https://nodejs.org/docs/latest-v15.x/api/console.html">15.x</a></li> <li><a href="https://nodejs.org/docs/latest-v14.x/api/console.html">14.x <b>LTS</b></a></li> <li><a href="https://nodejs.org/docs/latest-v13.x/api/console.html">13.x</a></li> <li><a href="https://nodejs.org/docs/latest-v12.x/api/console.html">12.x</a></li> <li><a href="https://nodejs.org/docs/latest-v11.x/api/console.html">11.x</a></li> <li><a href="https://nodejs.org/docs/latest-v10.x/api/console.html">10.x</a></li> <li><a href="https://nodejs.org/docs/latest-v9.x/api/console.html">9.x</a></li> <li><a href="https://nodejs.org/docs/latest-v8.x/api/console.html">8.x</a></li> <li><a href="https://nodejs.org/docs/latest-v7.x/api/console.html">7.x</a></li> <li><a href="https://nodejs.org/docs/latest-v6.x/api/console.html">6.x</a></li> <li><a href="https://nodejs.org/docs/latest-v5.x/api/console.html">5.x</a></li> <li><a href="https://nodejs.org/docs/latest-v4.x/api/console.html">4.x</a></li> <li><a href="https://nodejs.org/docs/latest-v0.12.x/api/console.html">0.12.x</a></li> <li><a href="https://nodejs.org/docs/latest-v0.10.x/api/console.html">0.10.x</a></li></ol></div> </li> <li class="picker-header"> <a href="#"> <span class="collapsed-arrow">►</span><span class="expanded-arrow">▼</span> Options </a> <div class="picker"> <ul> <li> <a href="all.html">View on single page</a> </li> <li> <a href="console.json">View as JSON</a> </li> <li class="edit_on_github"><a href="https://github.com/nodejs/node/edit/main/doc/api/console.md">Edit on GitHub</a></li> </ul> </div> </li> </ul> </div> <hr> </header> <details id="toc" open><summary>Table of contents</summary><ul> <li><span class="stability_2"><a href="#console">Console</a></span> <ul> <li><a href="#class-console">Class: <code>Console</code></a> <ul> <li><a href="#new-consolestdout-stderr-ignoreerrors"><code>new Console(stdout[, stderr][, ignoreErrors])</code></a></li> <li><a href="#new-consoleoptions"><code>new Console(options)</code></a></li> <li><a href="#consoleassertvalue-message"><code>console.assert(value[, ...message])</code></a></li> <li><a href="#consoleclear"><code>console.clear()</code></a></li> <li><a href="#consolecountlabel"><code>console.count([label])</code></a></li> <li><a href="#consolecountresetlabel"><code>console.countReset([label])</code></a></li> <li><a href="#consoledebugdata-args"><code>console.debug(data[, ...args])</code></a></li> <li><a href="#consoledirobj-options"><code>console.dir(obj[, options])</code></a></li> <li><a href="#consoledirxmldata"><code>console.dirxml(...data)</code></a></li> <li><a href="#consoleerrordata-args"><code>console.error([data][, ...args])</code></a></li> <li><a href="#consolegrouplabel"><code>console.group([...label])</code></a></li> <li><a href="#consolegroupcollapsed"><code>console.groupCollapsed()</code></a></li> <li><a href="#consolegroupend"><code>console.groupEnd()</code></a></li> <li><a href="#consoleinfodata-args"><code>console.info([data][, ...args])</code></a></li> <li><a href="#consolelogdata-args"><code>console.log([data][, ...args])</code></a></li> <li><a href="#consoletabletabulardata-properties"><code>console.table(tabularData[, properties])</code></a></li> <li><a href="#consoletimelabel"><code>console.time([label])</code></a></li> <li><a href="#consoletimeendlabel"><code>console.timeEnd([label])</code></a></li> <li><a href="#consoletimeloglabel-data"><code>console.timeLog([label][, ...data])</code></a></li> <li><a href="#consoletracemessage-args"><code>console.trace([message][, ...args])</code></a></li> <li><a href="#consolewarndata-args"><code>console.warn([data][, ...args])</code></a></li> </ul> </li> <li><a href="#inspector-only-methods">Inspector only methods</a> <ul> <li><a href="#consoleprofilelabel"><code>console.profile([label])</code></a></li> <li><a href="#consoleprofileendlabel"><code>console.profileEnd([label])</code></a></li> <li><a href="#consoletimestamplabel"><code>console.timeStamp([label])</code></a></li> </ul> </li> </ul> </li> </ul></details> <div id="apicontent"> <h2>Console<span><a class="mark" href="#console" id="console">#</a></span><a aria-hidden="true" class="legacy" id="console_console"></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/v16.20.0/lib/console.js">lib/console.js</a></p> <p>The <code>node:console</code> module provides a simple debugging console that is similar to the JavaScript console mechanism provided by web browsers.</p> <p>The module exports two specific components:</p> <ul> <li>A <code>Console</code> class with methods such as <code>console.log()</code>, <code>console.error()</code>, and <code>console.warn()</code> that can be used to write to any Node.js stream.</li> <li>A global <code>console</code> instance configured to write to <a href="process.html#processstdout"><code>process.stdout</code></a> and <a href="process.html#processstderr"><code>process.stderr</code></a>. The global <code>console</code> can be used without calling <code>require('node:console')</code>.</li> </ul> <p><em><strong>Warning</strong></em>: The global console object's methods are neither consistently synchronous like the browser APIs they resemble, nor are they consistently asynchronous like all other Node.js streams. See the <a href="process.html#a-note-on-process-io">note on process I/O</a> for more information.</p> <p>Example using the global <code>console</code>:</p> <pre><code class="language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'hello world'</span>); <span class="hljs-comment">// Prints: hello world, to stdout</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'hello %s'</span>, <span class="hljs-string">'world'</span>); <span class="hljs-comment">// Prints: hello world, to stdout</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">error</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Whoops, something bad happened'</span>)); <span class="hljs-comment">// Prints error message and stack trace to stderr:</span> <span class="hljs-comment">// Error: Whoops, something bad happened</span> <span class="hljs-comment">// at [eval]:5:15</span> <span class="hljs-comment">// at Script.runInThisContext (node:vm:132:18)</span> <span class="hljs-comment">// at Object.runInThisContext (node:vm:309:38)</span> <span class="hljs-comment">// at node:internal/process/execution:77:19</span> <span class="hljs-comment">// at [eval]-wrapper:6:22</span> <span class="hljs-comment">// at evalScript (node:internal/process/execution:76:60)</span> <span class="hljs-comment">// at node:internal/main/eval_string:23:3</span> <span class="hljs-keyword">const</span> name = <span class="hljs-string">'Will Robinson'</span>; <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">warn</span>(<span class="hljs-string">`Danger <span class="hljs-subst">${name}</span>! Danger!`</span>); <span class="hljs-comment">// Prints: Danger Will Robinson! Danger!, to stderr</span></code></pre> <p>Example using the <code>Console</code> class:</p> <pre><code class="language-js"><span class="hljs-keyword">const</span> out = <span class="hljs-title function_">getStreamSomehow</span>(); <span class="hljs-keyword">const</span> err = <span class="hljs-title function_">getStreamSomehow</span>(); <span class="hljs-keyword">const</span> myConsole = <span class="hljs-keyword">new</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title class_">Console</span>(out, err); myConsole.<span class="hljs-title function_">log</span>(<span class="hljs-string">'hello world'</span>); <span class="hljs-comment">// Prints: hello world, to out</span> myConsole.<span class="hljs-title function_">log</span>(<span class="hljs-string">'hello %s'</span>, <span class="hljs-string">'world'</span>); <span class="hljs-comment">// Prints: hello world, to out</span> myConsole.<span class="hljs-title function_">error</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Whoops, something bad happened'</span>)); <span class="hljs-comment">// Prints: [Error: Whoops, something bad happened], to err</span> <span class="hljs-keyword">const</span> name = <span class="hljs-string">'Will Robinson'</span>; myConsole.<span class="hljs-title function_">warn</span>(<span class="hljs-string">`Danger <span class="hljs-subst">${name}</span>! Danger!`</span>); <span class="hljs-comment">// Prints: Danger Will Robinson! Danger!, to err</span></code></pre> <section><h3>Class: <code>Console</code><span><a class="mark" href="#class-console" id="class-console">#</a></span><a aria-hidden="true" class="legacy" id="console_class_console"></a></h3> <div class="api_metadata"> <details class="changelog"><summary>History</summary> <table> <tbody><tr><th>Version</th><th>Changes</th></tr> <tr><td>v8.0.0</td> <td><p>Errors that occur while writing to the underlying streams will now be ignored by default.</p></td></tr> </tbody></table> </details> </div> <p>The <code>Console</code> class can be used to create a simple logger with configurable output streams and can be accessed using either <code>require('node:console').Console</code> or <code>console.Console</code> (or their destructured counterparts):</p> <pre><code class="language-js"><span class="hljs-keyword">const</span> { <span class="hljs-title class_">Console</span> } = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:console'</span>);</code></pre> <pre><code class="language-js"><span class="hljs-keyword">const</span> { <span class="hljs-title class_">Console</span> } = <span class="hljs-variable language_">console</span>;</code></pre> <h4><code>new Console(stdout[, stderr][, ignoreErrors])</code><span><a class="mark" href="#new-consolestdout-stderr-ignoreerrors" id="new-consolestdout-stderr-ignoreerrors">#</a></span><a aria-hidden="true" class="legacy" id="console_new_console_stdout_stderr_ignoreerrors"></a></h4> <h4><code>new Console(options)</code><span><a class="mark" href="#new-consoleoptions" id="new-consoleoptions">#</a></span><a aria-hidden="true" class="legacy" id="console_new_console_options"></a></h4> <div class="api_metadata"> <details class="changelog"><summary>History</summary> <table> <tbody><tr><th>Version</th><th>Changes</th></tr> <tr><td>v14.2.0, v12.17.0</td> <td><p>The <code>groupIndentation</code> option was introduced.</p></td></tr> <tr><td>v11.7.0</td> <td><p>The <code>inspectOptions</code> option is introduced.</p></td></tr> <tr><td>v10.0.0</td> <td><p>The <code>Console</code> constructor now supports an <code>options</code> argument, and the <code>colorMode</code> option was introduced.</p></td></tr> <tr><td>v8.0.0</td> <td><p>The <code>ignoreErrors</code> option was introduced.</p></td></tr> </tbody></table> </details> </div> <ul> <li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> <ul> <li><code>stdout</code> <a href="stream.html#class-streamwritable" class="type"><stream.Writable></a></li> <li><code>stderr</code> <a href="stream.html#class-streamwritable" class="type"><stream.Writable></a></li> <li><code>ignoreErrors</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> Ignore errors when writing to the underlying streams. <strong>Default:</strong> <code>true</code>.</li> <li><code>colorMode</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Set color support for this <code>Console</code> instance. Setting to <code>true</code> enables coloring while inspecting values. Setting to <code>false</code> disables coloring while inspecting values. Setting to <code>'auto'</code> makes color support depend on the value of the <code>isTTY</code> property and the value returned by <code>getColorDepth()</code> on the respective stream. This option can not be used, if <code>inspectOptions.colors</code> is set as well. <strong>Default:</strong> <code>'auto'</code>.</li> <li><code>inspectOptions</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> Specifies options that are passed along to <a href="util.html#utilinspectobject-options"><code>util.inspect()</code></a>.</li> <li><code>groupIndentation</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Set group indentation. <strong>Default:</strong> <code>2</code>.</li> </ul> </li> </ul> <p>Creates a new <code>Console</code> with one or two writable stream instances. <code>stdout</code> is a writable stream to print log or info output. <code>stderr</code> is used for warning or error output. If <code>stderr</code> is not provided, <code>stdout</code> is used for <code>stderr</code>.</p> <pre><code class="language-js"><span class="hljs-keyword">const</span> output = fs.<span class="hljs-title function_">createWriteStream</span>(<span class="hljs-string">'./stdout.log'</span>); <span class="hljs-keyword">const</span> errorOutput = fs.<span class="hljs-title function_">createWriteStream</span>(<span class="hljs-string">'./stderr.log'</span>); <span class="hljs-comment">// Custom simple logger</span> <span class="hljs-keyword">const</span> logger = <span class="hljs-keyword">new</span> <span class="hljs-title class_">Console</span>({ <span class="hljs-attr">stdout</span>: output, <span class="hljs-attr">stderr</span>: errorOutput }); <span class="hljs-comment">// use it like console</span> <span class="hljs-keyword">const</span> count = <span class="hljs-number">5</span>; logger.<span class="hljs-title function_">log</span>(<span class="hljs-string">'count: %d'</span>, count); <span class="hljs-comment">// In stdout.log: count 5</span></code></pre> <p>The global <code>console</code> is a special <code>Console</code> whose output is sent to <a href="process.html#processstdout"><code>process.stdout</code></a> and <a href="process.html#processstderr"><code>process.stderr</code></a>. It is equivalent to calling:</p> <pre><code class="language-js"><span class="hljs-keyword">new</span> <span class="hljs-title class_">Console</span>({ <span class="hljs-attr">stdout</span>: process.<span class="hljs-property">stdout</span>, <span class="hljs-attr">stderr</span>: process.<span class="hljs-property">stderr</span> });</code></pre> <h4><code>console.assert(value[, ...message])</code><span><a class="mark" href="#consoleassertvalue-message" id="consoleassertvalue-message">#</a></span><a aria-hidden="true" class="legacy" id="console_console_assert_value_message"></a></h4> <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 implementation is now spec compliant and does not throw anymore.</p></td></tr> <tr><td>v0.1.101</td> <td><p><span>Added in: v0.1.101</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"><any></a> The value tested for being truthy.</li> <li><code>...message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> All arguments besides <code>value</code> are used as error message.</li> </ul> <p><code>console.assert()</code> writes a message if <code>value</code> is <a href="https://developer.mozilla.org/en-US/docs/Glossary/Falsy">falsy</a> or omitted. It only writes a message and does not otherwise affect execution. The output always starts with <code>"Assertion failed"</code>. If provided, <code>message</code> is formatted using <a href="util.html#utilformatformat-args"><code>util.format()</code></a>.</p> <p>If <code>value</code> is <a href="https://developer.mozilla.org/en-US/docs/Glossary/Truthy">truthy</a>, nothing happens.</p> <pre><code class="language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">assert</span>(<span class="hljs-literal">true</span>, <span class="hljs-string">'does nothing'</span>); <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">assert</span>(<span class="hljs-literal">false</span>, <span class="hljs-string">'Whoops %s work'</span>, <span class="hljs-string">'didn\'t'</span>); <span class="hljs-comment">// Assertion failed: Whoops didn't work</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">assert</span>(); <span class="hljs-comment">// Assertion failed</span></code></pre> <h4><code>console.clear()</code><span><a class="mark" href="#consoleclear" id="consoleclear">#</a></span><a aria-hidden="true" class="legacy" id="console_console_clear"></a></h4> <div class="api_metadata"> <span>Added in: v8.3.0</span> </div> <p>When <code>stdout</code> is a TTY, calling <code>console.clear()</code> will attempt to clear the TTY. When <code>stdout</code> is not a TTY, this method does nothing.</p> <p>The specific operation of <code>console.clear()</code> can vary across operating systems and terminal types. For most Linux operating systems, <code>console.clear()</code> operates similarly to the <code>clear</code> shell command. On Windows, <code>console.clear()</code> will clear only the output in the current terminal viewport for the Node.js binary.</p> <h4><code>console.count([label])</code><span><a class="mark" href="#consolecountlabel" id="consolecountlabel">#</a></span><a aria-hidden="true" class="legacy" id="console_console_count_label"></a></h4> <div class="api_metadata"> <span>Added in: v8.3.0</span> </div> <ul> <li><code>label</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The display label for the counter. <strong>Default:</strong> <code>'default'</code>.</li> </ul> <p>Maintains an internal counter specific to <code>label</code> and outputs to <code>stdout</code> the number of times <code>console.count()</code> has been called with the given <code>label</code>.</p> <!-- eslint-skip --> <pre><code class="language-js">> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">count</span>() <span class="hljs-attr">default</span>: <span class="hljs-number">1</span> <span class="hljs-literal">undefined</span> > <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">count</span>(<span class="hljs-string">'default'</span>) <span class="hljs-attr">default</span>: <span class="hljs-number">2</span> <span class="hljs-literal">undefined</span> > <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">count</span>(<span class="hljs-string">'abc'</span>) <span class="hljs-attr">abc</span>: <span class="hljs-number">1</span> <span class="hljs-literal">undefined</span> > <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">count</span>(<span class="hljs-string">'xyz'</span>) <span class="hljs-attr">xyz</span>: <span class="hljs-number">1</span> <span class="hljs-literal">undefined</span> > <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">count</span>(<span class="hljs-string">'abc'</span>) <span class="hljs-attr">abc</span>: <span class="hljs-number">2</span> <span class="hljs-literal">undefined</span> > <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">count</span>() <span class="hljs-attr">default</span>: <span class="hljs-number">3</span> <span class="hljs-literal">undefined</span> ></code></pre> <h4><code>console.countReset([label])</code><span><a class="mark" href="#consolecountresetlabel" id="consolecountresetlabel">#</a></span><a aria-hidden="true" class="legacy" id="console_console_countreset_label"></a></h4> <div class="api_metadata"> <span>Added in: v8.3.0</span> </div> <ul> <li><code>label</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The display label for the counter. <strong>Default:</strong> <code>'default'</code>.</li> </ul> <p>Resets the internal counter specific to <code>label</code>.</p> <!-- eslint-skip --> <pre><code class="language-js">> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">count</span>(<span class="hljs-string">'abc'</span>); <span class="hljs-attr">abc</span>: <span class="hljs-number">1</span> <span class="hljs-literal">undefined</span> > <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">countReset</span>(<span class="hljs-string">'abc'</span>); <span class="hljs-literal">undefined</span> > <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">count</span>(<span class="hljs-string">'abc'</span>); <span class="hljs-attr">abc</span>: <span class="hljs-number">1</span> <span class="hljs-literal">undefined</span> ></code></pre> <h4><code>console.debug(data[, ...args])</code><span><a class="mark" href="#consoledebugdata-args" id="consoledebugdata-args">#</a></span><a aria-hidden="true" class="legacy" id="console_console_debug_data_args"></a></h4> <div class="api_metadata"> <details class="changelog"><summary>History</summary> <table> <tbody><tr><th>Version</th><th>Changes</th></tr> <tr><td>v8.10.0</td> <td><p><code>console.debug</code> is now an alias for <code>console.log</code>.</p></td></tr> <tr><td>v8.0.0</td> <td><p><span>Added in: v8.0.0</span></p></td></tr> </tbody></table> </details> </div> <ul> <li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> <li><code>...args</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> </ul> <p>The <code>console.debug()</code> function is an alias for <a href="#consolelogdata-args"><code>console.log()</code></a>.</p> <h4><code>console.dir(obj[, options])</code><span><a class="mark" href="#consoledirobj-options" id="consoledirobj-options">#</a></span><a aria-hidden="true" class="legacy" id="console_console_dir_obj_options"></a></h4> <div class="api_metadata"> <span>Added in: v0.1.101</span> </div> <ul> <li><code>obj</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> <li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> <ul> <li><code>showHidden</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If <code>true</code> then the object's non-enumerable and symbol properties will be shown too. <strong>Default:</strong> <code>false</code>.</li> <li><code>depth</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> Tells <a href="util.html#utilinspectobject-options"><code>util.inspect()</code></a> how many times to recurse while formatting the object. This is useful for inspecting large complicated objects. To make it recurse indefinitely, pass <code>null</code>. <strong>Default:</strong> <code>2</code>.</li> <li><code>colors</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> If <code>true</code>, then the output will be styled with ANSI color codes. Colors are customizable; see <a href="util.html#customizing-utilinspect-colors">customizing <code>util.inspect()</code> colors</a>. <strong>Default:</strong> <code>false</code>.</li> </ul> </li> </ul> <p>Uses <a href="util.html#utilinspectobject-options"><code>util.inspect()</code></a> on <code>obj</code> and prints the resulting string to <code>stdout</code>. This function bypasses any custom <code>inspect()</code> function defined on <code>obj</code>.</p> <h4><code>console.dirxml(...data)</code><span><a class="mark" href="#consoledirxmldata" id="consoledirxmldata">#</a></span><a aria-hidden="true" class="legacy" id="console_console_dirxml_data"></a></h4> <div class="api_metadata"> <details class="changelog"><summary>History</summary> <table> <tbody><tr><th>Version</th><th>Changes</th></tr> <tr><td>v9.3.0</td> <td><p><code>console.dirxml</code> now calls <code>console.log</code> for its arguments.</p></td></tr> <tr><td>v8.0.0</td> <td><p><span>Added in: v8.0.0</span></p></td></tr> </tbody></table> </details> </div> <ul> <li><code>...data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> </ul> <p>This method calls <code>console.log()</code> passing it the arguments received. This method does not produce any XML formatting.</p> <h4><code>console.error([data][, ...args])</code><span><a class="mark" href="#consoleerrordata-args" id="consoleerrordata-args">#</a></span><a aria-hidden="true" class="legacy" id="console_console_error_data_args"></a></h4> <div class="api_metadata"> <span>Added in: v0.1.100</span> </div> <ul> <li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> <li><code>...args</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> </ul> <p>Prints to <code>stderr</code> with newline. Multiple arguments can be passed, with the first used as the primary message and all additional used as substitution values similar to <a href="http://man7.org/linux/man-pages/man3/printf.3.html"><code>printf(3)</code></a> (the arguments are all passed to <a href="util.html#utilformatformat-args"><code>util.format()</code></a>).</p> <pre><code class="language-js"><span class="hljs-keyword">const</span> code = <span class="hljs-number">5</span>; <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">error</span>(<span class="hljs-string">'error #%d'</span>, code); <span class="hljs-comment">// Prints: error #5, to stderr</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">error</span>(<span class="hljs-string">'error'</span>, code); <span class="hljs-comment">// Prints: error 5, to stderr</span></code></pre> <p>If formatting elements (e.g. <code>%d</code>) are not found in the first string then <a href="util.html#utilinspectobject-options"><code>util.inspect()</code></a> is called on each argument and the resulting string values are concatenated. See <a href="util.html#utilformatformat-args"><code>util.format()</code></a> for more information.</p> <h4><code>console.group([...label])</code><span><a class="mark" href="#consolegrouplabel" id="consolegrouplabel">#</a></span><a aria-hidden="true" class="legacy" id="console_console_group_label"></a></h4> <div class="api_metadata"> <span>Added in: v8.5.0</span> </div> <ul> <li><code>...label</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> </ul> <p>Increases indentation of subsequent lines by spaces for <code>groupIndentation</code> length.</p> <p>If one or more <code>label</code>s are provided, those are printed first without the additional indentation.</p> <h4><code>console.groupCollapsed()</code><span><a class="mark" href="#consolegroupcollapsed" id="consolegroupcollapsed">#</a></span><a aria-hidden="true" class="legacy" id="console_console_groupcollapsed"></a></h4> <div class="api_metadata"> <span>Added in: v8.5.0</span> </div> <p>An alias for <a href="#consolegrouplabel"><code>console.group()</code></a>.</p> <h4><code>console.groupEnd()</code><span><a class="mark" href="#consolegroupend" id="consolegroupend">#</a></span><a aria-hidden="true" class="legacy" id="console_console_groupend"></a></h4> <div class="api_metadata"> <span>Added in: v8.5.0</span> </div> <p>Decreases indentation of subsequent lines by spaces for <code>groupIndentation</code> length.</p> <h4><code>console.info([data][, ...args])</code><span><a class="mark" href="#consoleinfodata-args" id="consoleinfodata-args">#</a></span><a aria-hidden="true" class="legacy" id="console_console_info_data_args"></a></h4> <div class="api_metadata"> <span>Added in: v0.1.100</span> </div> <ul> <li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> <li><code>...args</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> </ul> <p>The <code>console.info()</code> function is an alias for <a href="#consolelogdata-args"><code>console.log()</code></a>.</p> <h4><code>console.log([data][, ...args])</code><span><a class="mark" href="#consolelogdata-args" id="consolelogdata-args">#</a></span><a aria-hidden="true" class="legacy" id="console_console_log_data_args"></a></h4> <div class="api_metadata"> <span>Added in: v0.1.100</span> </div> <ul> <li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> <li><code>...args</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> </ul> <p>Prints to <code>stdout</code> with newline. Multiple arguments can be passed, with the first used as the primary message and all additional used as substitution values similar to <a href="http://man7.org/linux/man-pages/man3/printf.3.html"><code>printf(3)</code></a> (the arguments are all passed to <a href="util.html#utilformatformat-args"><code>util.format()</code></a>).</p> <pre><code class="language-js"><span class="hljs-keyword">const</span> count = <span class="hljs-number">5</span>; <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'count: %d'</span>, count); <span class="hljs-comment">// Prints: count: 5, to stdout</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-string">'count:'</span>, count); <span class="hljs-comment">// Prints: count: 5, to stdout</span></code></pre> <p>See <a href="util.html#utilformatformat-args"><code>util.format()</code></a> for more information.</p> <h4><code>console.table(tabularData[, properties])</code><span><a class="mark" href="#consoletabletabulardata-properties" id="consoletabletabulardata-properties">#</a></span><a aria-hidden="true" class="legacy" id="console_console_table_tabulardata_properties"></a></h4> <div class="api_metadata"> <span>Added in: v10.0.0</span> </div> <ul> <li><code>tabularData</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> <li><code>properties</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string[]></a> Alternate properties for constructing the table.</li> </ul> <p>Try to construct a table with the columns of the properties of <code>tabularData</code> (or use <code>properties</code>) and rows of <code>tabularData</code> and log it. Falls back to just logging the argument if it can't be parsed as tabular.</p> <pre><code class="language-js"><span class="hljs-comment">// These can't be parsed as tabular data</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">table</span>(<span class="hljs-title class_">Symbol</span>()); <span class="hljs-comment">// Symbol()</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">table</span>(<span class="hljs-literal">undefined</span>); <span class="hljs-comment">// undefined</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">table</span>([{ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span>, <span class="hljs-attr">b</span>: <span class="hljs-string">'Y'</span> }, { <span class="hljs-attr">a</span>: <span class="hljs-string">'Z'</span>, <span class="hljs-attr">b</span>: <span class="hljs-number">2</span> }]); <span class="hljs-comment">// ┌─────────┬─────┬─────┐</span> <span class="hljs-comment">// │ (index) │ a │ b │</span> <span class="hljs-comment">// ├─────────┼─────┼─────┤</span> <span class="hljs-comment">// │ 0 │ 1 │ 'Y' │</span> <span class="hljs-comment">// │ 1 │ 'Z' │ 2 │</span> <span class="hljs-comment">// └─────────┴─────┴─────┘</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">table</span>([{ <span class="hljs-attr">a</span>: <span class="hljs-number">1</span>, <span class="hljs-attr">b</span>: <span class="hljs-string">'Y'</span> }, { <span class="hljs-attr">a</span>: <span class="hljs-string">'Z'</span>, <span class="hljs-attr">b</span>: <span class="hljs-number">2</span> }], [<span class="hljs-string">'a'</span>]); <span class="hljs-comment">// ┌─────────┬─────┐</span> <span class="hljs-comment">// │ (index) │ a │</span> <span class="hljs-comment">// ├─────────┼─────┤</span> <span class="hljs-comment">// │ 0 │ 1 │</span> <span class="hljs-comment">// │ 1 │ 'Z' │</span> <span class="hljs-comment">// └─────────┴─────┘</span></code></pre> <h4><code>console.time([label])</code><span><a class="mark" href="#consoletimelabel" id="consoletimelabel">#</a></span><a aria-hidden="true" class="legacy" id="console_console_time_label"></a></h4> <div class="api_metadata"> <span>Added in: v0.1.104</span> </div> <ul> <li><code>label</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> <strong>Default:</strong> <code>'default'</code></li> </ul> <p>Starts a timer that can be used to compute the duration of an operation. Timers are identified by a unique <code>label</code>. Use the same <code>label</code> when calling <a href="#consoletimeendlabel"><code>console.timeEnd()</code></a> to stop the timer and output the elapsed time in suitable time units to <code>stdout</code>. For example, if the elapsed time is 3869ms, <code>console.timeEnd()</code> displays "3.869s".</p> <h4><code>console.timeEnd([label])</code><span><a class="mark" href="#consoletimeendlabel" id="consoletimeendlabel">#</a></span><a aria-hidden="true" class="legacy" id="console_console_timeend_label"></a></h4> <div class="api_metadata"> <details class="changelog"><summary>History</summary> <table> <tbody><tr><th>Version</th><th>Changes</th></tr> <tr><td>v13.0.0</td> <td><p>The elapsed time is displayed with a suitable time unit.</p></td></tr> <tr><td>v6.0.0</td> <td><p>This method no longer supports multiple calls that don't map to individual <code>console.time()</code> calls; see below for details.</p></td></tr> <tr><td>v0.1.104</td> <td><p><span>Added in: v0.1.104</span></p></td></tr> </tbody></table> </details> </div> <ul> <li><code>label</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> <strong>Default:</strong> <code>'default'</code></li> </ul> <p>Stops a timer that was previously started by calling <a href="#consoletimelabel"><code>console.time()</code></a> and prints the result to <code>stdout</code>:</p> <pre><code class="language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">time</span>(<span class="hljs-string">'bunch-of-stuff'</span>); <span class="hljs-comment">// Do a bunch of stuff.</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">timeEnd</span>(<span class="hljs-string">'bunch-of-stuff'</span>); <span class="hljs-comment">// Prints: bunch-of-stuff: 225.438ms</span></code></pre> <h4><code>console.timeLog([label][, ...data])</code><span><a class="mark" href="#consoletimeloglabel-data" id="consoletimeloglabel-data">#</a></span><a aria-hidden="true" class="legacy" id="console_console_timelog_label_data"></a></h4> <div class="api_metadata"> <span>Added in: v10.7.0</span> </div> <ul> <li><code>label</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> <strong>Default:</strong> <code>'default'</code></li> <li><code>...data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> </ul> <p>For a timer that was previously started by calling <a href="#consoletimelabel"><code>console.time()</code></a>, prints the elapsed time and other <code>data</code> arguments to <code>stdout</code>:</p> <pre><code class="language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">time</span>(<span class="hljs-string">'process'</span>); <span class="hljs-keyword">const</span> value = <span class="hljs-title function_">expensiveProcess1</span>(); <span class="hljs-comment">// Returns 42</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">timeLog</span>(<span class="hljs-string">'process'</span>, value); <span class="hljs-comment">// Prints "process: 365.227ms 42".</span> <span class="hljs-title function_">doExpensiveProcess2</span>(value); <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">timeEnd</span>(<span class="hljs-string">'process'</span>);</code></pre> <h4><code>console.trace([message][, ...args])</code><span><a class="mark" href="#consoletracemessage-args" id="consoletracemessage-args">#</a></span><a aria-hidden="true" class="legacy" id="console_console_trace_message_args"></a></h4> <div class="api_metadata"> <span>Added in: v0.1.104</span> </div> <ul> <li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> <li><code>...args</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> </ul> <p>Prints to <code>stderr</code> the string <code>'Trace: '</code>, followed by the <a href="util.html#utilformatformat-args"><code>util.format()</code></a> formatted message and stack trace to the current position in the code.</p> <pre><code class="language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">trace</span>(<span class="hljs-string">'Show me'</span>); <span class="hljs-comment">// Prints: (stack trace will vary based on where trace is called)</span> <span class="hljs-comment">// Trace: Show me</span> <span class="hljs-comment">// at repl:2:9</span> <span class="hljs-comment">// at REPLServer.defaultEval (repl.js:248:27)</span> <span class="hljs-comment">// at bound (domain.js:287:14)</span> <span class="hljs-comment">// at REPLServer.runBound [as eval] (domain.js:300:12)</span> <span class="hljs-comment">// at REPLServer.<anonymous> (repl.js:412:12)</span> <span class="hljs-comment">// at emitOne (events.js:82:20)</span> <span class="hljs-comment">// at REPLServer.emit (events.js:169:7)</span> <span class="hljs-comment">// at REPLServer.Interface._onLine (readline.js:210:10)</span> <span class="hljs-comment">// at REPLServer.Interface._line (readline.js:549:8)</span> <span class="hljs-comment">// at REPLServer.Interface._ttyWrite (readline.js:826:14)</span></code></pre> <h4><code>console.warn([data][, ...args])</code><span><a class="mark" href="#consolewarndata-args" id="consolewarndata-args">#</a></span><a aria-hidden="true" class="legacy" id="console_console_warn_data_args"></a></h4> <div class="api_metadata"> <span>Added in: v0.1.100</span> </div> <ul> <li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> <li><code>...args</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a></li> </ul> <p>The <code>console.warn()</code> function is an alias for <a href="#consoleerrordata-args"><code>console.error()</code></a>.</p> </section><section><h3>Inspector only methods<span><a class="mark" href="#inspector-only-methods" id="inspector-only-methods">#</a></span><a aria-hidden="true" class="legacy" id="console_inspector_only_methods"></a></h3> <p>The following methods are exposed by the V8 engine in the general API but do not display anything unless used in conjunction with the <a href="debugger.html">inspector</a> (<code>--inspect</code> flag).</p> <h4><code>console.profile([label])</code><span><a class="mark" href="#consoleprofilelabel" id="consoleprofilelabel">#</a></span><a aria-hidden="true" class="legacy" id="console_console_profile_label"></a></h4> <div class="api_metadata"> <span>Added in: v8.0.0</span> </div> <ul> <li><code>label</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>This method does not display anything unless used in the inspector. The <code>console.profile()</code> method starts a JavaScript CPU profile with an optional label until <a href="#consoleprofileendlabel"><code>console.profileEnd()</code></a> is called. The profile is then added to the <strong>Profile</strong> panel of the inspector.</p> <pre><code class="language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">profile</span>(<span class="hljs-string">'MyLabel'</span>); <span class="hljs-comment">// Some code</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">profileEnd</span>(<span class="hljs-string">'MyLabel'</span>); <span class="hljs-comment">// Adds the profile 'MyLabel' to the Profiles panel of the inspector.</span></code></pre> <h4><code>console.profileEnd([label])</code><span><a class="mark" href="#consoleprofileendlabel" id="consoleprofileendlabel">#</a></span><a aria-hidden="true" class="legacy" id="console_console_profileend_label"></a></h4> <div class="api_metadata"> <span>Added in: v8.0.0</span> </div> <ul> <li><code>label</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>This method does not display anything unless used in the inspector. Stops the current JavaScript CPU profiling session if one has been started and prints the report to the <strong>Profiles</strong> panel of the inspector. See <a href="#consoleprofilelabel"><code>console.profile()</code></a> for an example.</p> <p>If this method is called without a label, the most recently started profile is stopped.</p> <h4><code>console.timeStamp([label])</code><span><a class="mark" href="#consoletimestamplabel" id="consoletimestamplabel">#</a></span><a aria-hidden="true" class="legacy" id="console_console_timestamp_label"></a></h4> <div class="api_metadata"> <span>Added in: v8.0.0</span> </div> <ul> <li><code>label</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>This method does not display anything unless used in the inspector. The <code>console.timeStamp()</code> method adds an event with the label <code>'label'</code> to the <strong>Timeline</strong> panel of the inspector.</p></section> <!-- API END --> </div> </div> </div> </body> </html>
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