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<!doctype html> <html lang="en"> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width"> <title>Console | Node.js v10.24.1 Documentation</title> <link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Lato:400,700,400italic"> <link rel="stylesheet" href="assets/style.css"> <link rel="stylesheet" href="assets/sh.css"> <link rel="canonical" href="https://nodejs.org/api/console.html"> </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 these Docs</a></li> <li><a href="synopsis.html" class="nav-synopsis">Usage & Example</a></li> </ul> <div class="line"></div> <ul> <li><a href="assert.html" class="nav-assert">Assertion Testing</a></li> <li><a href="async_hooks.html" class="nav-async_hooks">Async 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class="nav-https-github-com-nodejs-node">GitHub Repo & Issue Tracker</a></li> </ul> </div> <div id="column1" data-id="console" class="interior"> <header> <h1>Node.js v10.24.1 Documentation</h1> <div id="gtoc"> <ul> <li> <a href="index.html" name="toc">Index</a> </li> <li> <a href="all.html">View on single page</a> </li> <li> <a href="console.json">View as JSON</a> </li> <li class="version-picker"> <a href="#">View another version <span>▼</span></a> <ol class="version-picker"><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 <b>LTS</b></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 <b>LTS</b></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> </li> <li class="edit_on_github"><a href="https://github.com/nodejs/node/edit/master/doc/api/console.md"><span class="github_icon"><svg height="16" width="16" viewBox="0 0 16.1 16.1" fill="currentColor"><path d="M8 0a8 8 0 0 0-2.5 15.6c.4 0 .5-.2.5-.4v-1.5c-2 .4-2.5-.5-2.7-1 0-.1-.5-.9-.8-1-.3-.2-.7-.6 0-.6.6 0 1 .6 1.2.8.7 1.2 1.9 1 2.4.7 0-.5.2-.9.5-1-1.8-.3-3.7-1-3.7-4 0-.9.3-1.6.8-2.2 0-.2-.3-1 .1-2 0 0 .7-.3 2.2.7a7.4 7.4 0 0 1 4 0c1.5-1 2.2-.8 2.2-.8.5 1.1.2 2 .1 2.1.5.6.8 1.3.8 2.2 0 3-1.9 3.7-3.6 4 .3.2.5.7.5 1.4v2.2c0 .2.1.5.5.4A8 8 0 0 0 16 8a8 8 0 0 0-8-8z"/></svg></span>Edit on GitHub</a></li> </ul> </div> <hr> </header> <div id="toc"> <h2>Table of Contents</h2> <ul> <li> <p><span class="stability_2"><a href="#console_console">Console</a></span></p> <ul> <li> <p><a href="#console_class_console">Class: Console</a></p> <ul> <li><a href="#console_new_console_stdout_stderr_ignoreerrors">new Console(stdout[, stderr][, ignoreErrors])</a></li> <li><a href="#console_new_console_options">new Console(options)</a></li> <li><a href="#console_console_assert_value_message">console.assert(value[, ...message])</a></li> <li><a href="#console_console_clear">console.clear()</a></li> <li><a href="#console_console_count_label">console.count([label])</a></li> <li><a href="#console_console_countreset_label">console.countReset([label])</a></li> <li><a href="#console_console_debug_data_args">console.debug(data[, ...args])</a></li> <li><a href="#console_console_dir_obj_options">console.dir(obj[, options])</a></li> <li><a href="#console_console_dirxml_data">console.dirxml(...data)</a></li> <li><a href="#console_console_error_data_args">console.error([data][, ...args])</a></li> <li><a href="#console_console_group_label">console.group([...label])</a></li> <li><a href="#console_console_groupcollapsed">console.groupCollapsed()</a></li> <li><a href="#console_console_groupend">console.groupEnd()</a></li> <li><a href="#console_console_info_data_args">console.info([data][, ...args])</a></li> <li><a href="#console_console_log_data_args">console.log([data][, ...args])</a></li> <li><a href="#console_console_table_tabulardata_properties">console.table(tabularData[, properties])</a></li> <li><a href="#console_console_time_label">console.time([label])</a></li> <li><a href="#console_console_timeend_label">console.timeEnd([label])</a></li> <li><a href="#console_console_timelog_label_data">console.timeLog([label][, ...data])</a></li> <li><a href="#console_console_trace_message_args">console.trace([message][, ...args])</a></li> <li><a href="#console_console_warn_data_args">console.warn([data][, ...args])</a></li> </ul> </li> <li> <p><a href="#console_inspector_only_methods">Inspector only methods</a></p> <ul> <li><a href="#console_console_marktimeline_label">console.markTimeline([label])</a></li> <li><a href="#console_console_profile_label">console.profile([label])</a></li> <li><a href="#console_console_profileend_label">console.profileEnd([label])</a></li> <li><a href="#console_console_timestamp_label">console.timeStamp([label])</a></li> <li><a href="#console_console_timeline_label">console.timeline([label])</a></li> <li><a href="#console_console_timelineend_label">console.timelineEnd([label])</a></li> </ul> </li> </ul> </li> </ul> </div> <div id="apicontent"> <h1>Console<span><a class="mark" href="#console_console" id="console_console">#</a></span></h1> <p></p><div class="api_stability api_stability_2"><a href="documentation.html#documentation_stability_index">Stability: 2</a> - Stable</div><p></p> <p>The <code>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#process_process_stdout"><code>process.stdout</code></a> and <a href="process.html#process_process_stderr"><code>process.stderr</code></a>. The global <code>console</code> can be used without calling <code>require('console')</code>.</li> </ul> <p><strong><em>Warning</em></strong>: 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#process_a_note_on_process_i_o">note on process I/O</a> for more information.</p> <p>Example using the global <code>console</code>:</p> <pre><code class="language-js">console.log('hello world'); // Prints: hello world, to stdout console.log('hello %s', 'world'); // Prints: hello world, to stdout console.error(new Error('Whoops, something bad happened')); // Prints: [Error: Whoops, something bad happened], to stderr const name = 'Will Robinson'; console.warn(`Danger ${name}! Danger!`); // Prints: Danger Will Robinson! Danger!, to stderr </code></pre> <p>Example using the <code>Console</code> class:</p> <pre><code class="language-js">const out = getStreamSomehow(); const err = getStreamSomehow(); const myConsole = new console.Console(out, err); myConsole.log('hello world'); // Prints: hello world, to out myConsole.log('hello %s', 'world'); // Prints: hello world, to out myConsole.error(new Error('Whoops, something bad happened')); // Prints: [Error: Whoops, something bad happened], to err const name = 'Will Robinson'; myConsole.warn(`Danger ${name}! Danger!`); // Prints: Danger Will Robinson! Danger!, to err </code></pre> <h2>Class: Console<span><a class="mark" href="#console_class_console" id="console_class_console">#</a></span></h2> <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('console').Console</code> or <code>console.Console</code> (or their destructured counterparts):</p> <pre><code class="language-js">const { Console } = require('console'); </code></pre> <pre><code class="language-js">const { Console } = console; </code></pre> <h3>new Console(stdout[, stderr][, ignoreerrors])<span><a class="mark" href="#console_new_console_stdout_stderr_ignoreerrors" id="console_new_console_stdout_stderr_ignoreerrors">#</a></span></h3> <h3>new Console(options)<span><a class="mark" href="#console_new_console_options" id="console_new_console_options">#</a></span></h3> <div class="api_metadata"> <details class="changelog"><summary>History</summary> <table> <tbody><tr><th>Version</th><th>Changes</th></tr> <tr><td>v10.0.0</td> <td><p>The <code>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> <p><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></p> <ul> <li><code>stdout</code> <a href="stream.html#stream_class_stream_writable" class="type"><stream.Writable></a></li> <li><code>stderr</code> <a href="stream.html#stream_class_stream_writable" 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>'auto'</code> will make color support depend on the value of the <code>isTTY</code> property and the value returned by <code>getColorDepth()</code> on the respective stream. <strong>Default:</strong> <code>'auto'</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">const output = fs.createWriteStream('./stdout.log'); const errorOutput = fs.createWriteStream('./stderr.log'); // custom simple logger const logger = new Console({ stdout: output, stderr: errorOutput }); // use it like console const count = 5; logger.log('count: %d', count); // in stdout.log: count 5 </code></pre> <p>The global <code>console</code> is a special <code>Console</code> whose output is sent to <a href="process.html#process_process_stdout"><code>process.stdout</code></a> and <a href="process.html#process_process_stderr"><code>process.stderr</code></a>. It is equivalent to calling:</p> <pre><code class="language-js">new Console({ stdout: process.stdout, stderr: process.stderr }); </code></pre> <h3>console.assert(value[, ...message])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L287">[src]</a><span><a class="mark" href="#console_console_assert_value_message" id="console_console_assert_value_message">#</a></span></h3> <div class="api_metadata"> <details class="changelog"><summary>History</summary> <table> <tbody><tr><th>Version</th><th>Changes</th></tr> <tr><td>v10.0.0</td> <td><p>The 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>A simple assertion test that verifies whether <code>value</code> is truthy. If it is not, <code>Assertion failed</code> is logged. If provided, the error <code>message</code> is formatted using <a href="util.html#util_util_format_format_args"><code>util.format()</code></a> by passing along all message arguments. The output is used as the error message.</p> <pre><code class="language-js">console.assert(true, 'does nothing'); // OK console.assert(false, 'Whoops %s work', 'didn\'t'); // Assertion failed: Whoops didn't work </code></pre> <p>Calling <code>console.assert()</code> with a falsy assertion will only cause the <code>message</code> to be printed to the console without interrupting execution of subsequent code.</p> <h3>console.clear()<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L295">[src]</a><span><a class="mark" href="#console_console_clear" id="console_console_clear">#</a></span></h3> <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> <h3>console.count([label])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L308">[src]</a><span><a class="mark" href="#console_console_count_label" id="console_console_count_label">#</a></span></h3> <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">> console.count() default: 1 undefined > console.count('default') default: 2 undefined > console.count('abc') abc: 1 undefined > console.count('xyz') xyz: 1 undefined > console.count('abc') abc: 2 undefined > console.count() default: 3 undefined > </code></pre> <h3>console.countReset([label])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L327">[src]</a><span><a class="mark" href="#console_console_countreset_label" id="console_console_countreset_label">#</a></span></h3> <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">> console.count('abc'); abc: 1 undefined > console.countReset('abc'); undefined > console.count('abc'); abc: 1 undefined > </code></pre> <h3>console.debug(data[, ...args])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L213">[src]</a><span><a class="mark" href="#console_console_debug_data_args" id="console_console_debug_data_args">#</a></span></h3> <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.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="#console_console_log_data_args"><code>console.log()</code></a>.</p> <h3>console.dir(obj[, options])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L226">[src]</a><span><a class="mark" href="#console_console_dir_obj_options" id="console_console_dir_obj_options">#</a></span></h3> <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> <p><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></p> <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#util_util_inspect_object_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#util_customizing_util_inspect_colors">customizing <code>util.inspect()</code> colors</a>. <strong>Default:</strong> <code>false</code>.</li> </ul> </li> </ul> <p>Uses <a href="util.html#util_util_inspect_object_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> <h3>console.dirxml(...data)<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L215">[src]</a><span><a class="mark" href="#console_console_dirxml_data" id="console_console_dirxml_data">#</a></span></h3> <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. Please note that this method does not produce any XML formatting.</p> <h3>console.error([data][, ...args])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L224">[src]</a><span><a class="mark" href="#console_console_error_data_args" id="console_console_error_data_args">#</a></span></h3> <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#util_util_format_format_args"><code>util.format()</code></a>).</p> <pre><code class="language-js">const code = 5; console.error('error #%d', code); // Prints: error #5, to stderr console.error('error', code); // Prints: error 5, to stderr </code></pre> <p>If formatting elements (e.g. <code>%d</code>) are not found in the first string then <a href="util.html#util_util_inspect_object_options"><code>util.inspect()</code></a> is called on each argument and the resulting string values are concatenated. See <a href="util.html#util_util_format_format_args"><code>util.format()</code></a> for more information.</p> <h3>console.group([...label])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L333">[src]</a><span><a class="mark" href="#console_console_group_label" id="console_console_group_label">#</a></span></h3> <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 two spaces.</p> <p>If one or more <code>label</code>s are provided, those are printed first without the additional indentation.</p> <h3>console.groupCollapsed()<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L339">[src]</a><span><a class="mark" href="#console_console_groupcollapsed" id="console_console_groupcollapsed">#</a></span></h3> <div class="api_metadata"> <span>Added in: v8.5.0</span> </div> <p>An alias for <a href="#console_console_group_label"><code>console.group()</code></a>.</p> <h3>console.groupEnd()<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L341">[src]</a><span><a class="mark" href="#console_console_groupend" id="console_console_groupend">#</a></span></h3> <div class="api_metadata"> <span>Added in: v8.5.0</span> </div> <p>Decreases indentation of subsequent lines by two spaces.</p> <h3>console.info([data][, ...args])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L214">[src]</a><span><a class="mark" href="#console_console_info_data_args" id="console_console_info_data_args">#</a></span></h3> <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="#console_console_log_data_args"><code>console.log()</code></a>.</p> <h3>console.log([data][, ...args])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L206">[src]</a><span><a class="mark" href="#console_console_log_data_args" id="console_console_log_data_args">#</a></span></h3> <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#util_util_format_format_args"><code>util.format()</code></a>).</p> <pre><code class="language-js">const count = 5; console.log('count: %d', count); // Prints: count: 5, to stdout console.log('count:', count); // Prints: count: 5, to stdout </code></pre> <p>See <a href="util.html#util_util_format_format_args"><code>util.format()</code></a> for more information.</p> <h3>console.table(tabularData[, properties])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L355">[src]</a><span><a class="mark" href="#console_console_table_tabulardata_properties" id="console_console_table_tabulardata_properties">#</a></span></h3> <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">// These can't be parsed as tabular data console.table(Symbol()); // Symbol() console.table(undefined); // undefined console.table([{ a: 1, b: 'Y' }, { a: 'Z', b: 2 }]); // ┌─────────┬─────┬─────┐ // │ (index) │ a │ b │ // ├─────────┼─────┼─────┤ // │ 0 │ 1 │ 'Y' │ // │ 1 │ 'Z' │ 2 │ // └─────────┴─────┴─────┘ console.table([{ a: 1, b: 'Y' }, { a: 'Z', b: 2 }], ['a']); // ┌─────────┬─────┐ // │ (index) │ a │ // ├─────────┼─────┤ // │ 0 │ 1 │ // │ 1 │ 'Z' │ // └─────────┴─────┘ </code></pre> <h3>console.time([label])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L237">[src]</a><span><a class="mark" href="#console_console_time_label" id="console_console_time_label">#</a></span></h3> <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="#console_console_timeend_label"><code>console.timeEnd()</code></a> to stop the timer and output the elapsed time in milliseconds to <code>stdout</code>. Timer durations are accurate to the sub-millisecond.</p> <h3>console.timeEnd([label])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L244">[src]</a><span><a class="mark" href="#console_console_timeend_label" id="console_console_timeend_label">#</a></span></h3> <div class="api_metadata"> <details class="changelog"><summary>History</summary> <table> <tbody><tr><th>Version</th><th>Changes</th></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="#console_console_time_label"><code>console.time()</code></a> and prints the result to <code>stdout</code>:</p> <pre><code class="language-js">console.time('100-elements'); for (let i = 0; i < 100; i++) {} console.timeEnd('100-elements'); // prints 100-elements: 225.438ms </code></pre> <h3>console.timeLog([label][, ...data])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L254">[src]</a><span><a class="mark" href="#console_console_timelog_label_data" id="console_console_timelog_label_data">#</a></span></h3> <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="#console_console_time_label"><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">console.time('process'); const value = expensiveProcess1(); // Returns 42 console.timeLog('process', value); // Prints "process: 365.227ms 42". doExpensiveProcess2(value); console.timeEnd('process'); </code></pre> <h3>console.trace([message][, ...args])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L278">[src]</a><span><a class="mark" href="#console_console_trace_message_args" id="console_console_trace_message_args">#</a></span></h3> <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#util_util_format_format_args"><code>util.format()</code></a> formatted message and stack trace to the current position in the code.</p> <pre><code class="language-js">console.trace('Show me'); // Prints: (stack trace will vary based on where trace is called) // Trace: Show me // at repl:2:9 // at REPLServer.defaultEval (repl.js:248:27) // at bound (domain.js:287:14) // at REPLServer.runBound [as eval] (domain.js:300:12) // at REPLServer.<anonymous> (repl.js:412:12) // at emitOne (events.js:82:20) // at REPLServer.emit (events.js:169:7) // at REPLServer.Interface._onLine (readline.js:210:10) // at REPLServer.Interface._line (readline.js:549:8) // at REPLServer.Interface._ttyWrite (readline.js:826:14) </code></pre> <h3>console.warn([data][, ...args])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/console.js#L217">[src]</a><span><a class="mark" href="#console_console_warn_data_args" id="console_console_warn_data_args">#</a></span></h3> <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="#console_console_error_data_args"><code>console.error()</code></a>.</p> <h2>Inspector only methods<span><a class="mark" href="#console_inspector_only_methods" id="console_inspector_only_methods">#</a></span></h2> <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> <h3>console.markTimeline([label])<span><a class="mark" href="#console_console_marktimeline_label" id="console_console_marktimeline_label">#</a></span></h3> <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> <strong>Default:</strong> <code>'default'</code></li> </ul> <p>This method does not display anything unless used in the inspector. The <code>console.markTimeline()</code> method is the deprecated form of <a href="#console_console_timestamp_label"><code>console.timeStamp()</code></a>.</p> <h3>console.profile([label])<span><a class="mark" href="#console_console_profile_label" id="console_console_profile_label">#</a></span></h3> <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="#console_console_profileend_label"><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">console.profile('MyLabel'); // Some code console.profileEnd('MyLabel'); // Adds the profile 'MyLabel' to the Profiles panel of the inspector. </code></pre> <h3>console.profileEnd([label])<span><a class="mark" href="#console_console_profileend_label" id="console_console_profileend_label">#</a></span></h3> <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="#console_console_profile_label"><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> <h3>console.timeStamp([label])<span><a class="mark" href="#console_console_timestamp_label" id="console_console_timestamp_label">#</a></span></h3> <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> <h3>console.timeline([label])<span><a class="mark" href="#console_console_timeline_label" id="console_console_timeline_label">#</a></span></h3> <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> <strong>Default:</strong> <code>'default'</code></li> </ul> <p>This method does not display anything unless used in the inspector. The <code>console.timeline()</code> method is the deprecated form of <a href="#console_console_time_label"><code>console.time()</code></a>.</p> <h3>console.timelineEnd([label])<span><a class="mark" href="#console_console_timelineend_label" id="console_console_timelineend_label">#</a></span></h3> <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> <strong>Default:</strong> <code>'default'</code></li> </ul> <p>This method does not display anything unless used in the inspector. The <code>console.timelineEnd()</code> method is the deprecated form of <a href="#console_console_timeend_label"><code>console.timeEnd()</code></a>.</p> </div> </div> </div> <script src="assets/sh_main.js"></script> <script src="assets/sh_javascript.min.js"></script> <script>highlight(undefined, undefined, 'pre');</script> </body> </html>