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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="v22.22.0"> <title>Console | 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/console.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> 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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="#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">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> 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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> 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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/console.html">25.x</a></li> <li><a href="https://nodejs.org/docs/latest-v24.x/api/console.html">24.x <b>LTS</b></a></li> <li><a href="https://nodejs.org/docs/latest-v23.x/api/console.html">23.x</a></li> <li><a href="https://nodejs.org/docs/latest-v22.x/api/console.html">22.x <b>LTS</b></a></li> <li><a href="https://nodejs.org/docs/latest-v21.x/api/console.html">21.x</a></li> <li><a href="https://nodejs.org/docs/latest-v20.x/api/console.html">20.x <b>LTS</b></a></li> <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</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</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</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="#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="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 role="navigation" 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 role="main" 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/v22.22.0/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. Programs that desire to depend on the synchronous / asynchronous behavior of the console functions should first figure out the nature of console's backing stream. This is because the stream is dependent on the underlying platform and standard stream configuration of the current process. 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">${name}</span>! Danger!`</span>); <span class="hljs-comment">// Prints: Danger Will Robinson! Danger!, to stderr</span></code> <button class="copy-button">copy</button></pre> <p>Example using the <code>Console</code> class:</p> <pre><code class="language-js"><span class="hljs-keyword">const</span> out = <span class="hljs-title function_">getStreamSomehow</span>(); <span class="hljs-keyword">const</span> err = <span class="hljs-title function_">getStreamSomehow</span>(); <span class="hljs-keyword">const</span> myConsole = <span class="hljs-keyword">new</span> <span class="hljs-variable language_">console</span>.<span class="hljs-title class_">Console</span>(out, err); myConsole.<span class="hljs-title function_">log</span>(<span class="hljs-string">'hello world'</span>); <span class="hljs-comment">// Prints: hello world, to out</span> myConsole.<span class="hljs-title function_">log</span>(<span class="hljs-string">'hello %s'</span>, <span class="hljs-string">'world'</span>); <span class="hljs-comment">// Prints: hello world, to out</span> myConsole.<span class="hljs-title function_">error</span>(<span class="hljs-keyword">new</span> <span class="hljs-title class_">Error</span>(<span class="hljs-string">'Whoops, something bad happened'</span>)); <span class="hljs-comment">// Prints: [Error: Whoops, something bad happened], to err</span> <span class="hljs-keyword">const</span> name = <span class="hljs-string">'Will Robinson'</span>; myConsole.<span class="hljs-title function_">warn</span>(<span class="hljs-string">`Danger <span class="hljs-subst">${name}</span>! Danger!`</span>); <span class="hljs-comment">// Prints: Danger Will Robinson! Danger!, to err</span></code> <button class="copy-button">copy</button></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 class="with-44-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> { <span class="hljs-title class_">Console</span> } <span class="hljs-keyword">from</span> <span class="hljs-string">'node:console'</span>;</code><code class="language-js cjs"><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><button class="copy-button">copy</button></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> <button class="copy-button">copy</button></pre> <div> <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> </div><div> <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 class="with-44-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> { createWriteStream } <span class="hljs-keyword">from</span> <span class="hljs-string">'node:fs'</span>; <span class="hljs-keyword">import</span> { <span class="hljs-title class_">Console</span> } <span class="hljs-keyword">from</span> <span class="hljs-string">'node:console'</span>; <span class="hljs-comment">// Alternatively</span> <span class="hljs-comment">// const { Console } = console;</span> <span class="hljs-keyword">const</span> output = <span class="hljs-title function_">createWriteStream</span>(<span class="hljs-string">'./stdout.log'</span>); <span class="hljs-keyword">const</span> errorOutput = <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><code class="language-js cjs"><span class="hljs-keyword">const</span> fs = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:fs'</span>); <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>); <span class="hljs-comment">// Alternatively</span> <span class="hljs-comment">// const { Console } = console;</span> <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><button class="copy-button">copy</button></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> <button class="copy-button">copy</button></pre> </div><div> <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> <button class="copy-button">copy</button></pre> </div><div> <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> </div><div> <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> <button class="copy-button">copy</button></pre> </div><div> <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> <button class="copy-button">copy</button></pre> </div><div> <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> </div><div> <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> </div><div> <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> </div><div> <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> <button class="copy-button">copy</button></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> </div><div> <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> </div><div> <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> </div><div> <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> </div><div> <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> </div><div> <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> <button class="copy-button">copy</button></pre> <p>See <a href="util.html#utilformatformat-args"><code>util.format()</code></a> for more information.</p> </div><div> <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> <button class="copy-button">copy</button></pre> </div><div> <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> </div><div> <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> <button class="copy-button">copy</button></pre> </div><div> <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> <button class="copy-button">copy</button></pre> </div><div> <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> <button class="copy-button">copy</button></pre> </div><div> <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> </div> </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> <div> <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> <button class="copy-button">copy</button></pre> </div><div> <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> </div><div> <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></div></section> <!-- API END --> </div> </div> </div> </body> </html>