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"> <link rel="stylesheet" href="data:text/css;base64,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"> <link rel="canonical" href="https://nodejs.org/api/process.html"> </head> <body class="alt apidoc" id="api-section-process"> <div id="content" class="clearfix"> <div id="column2" class="interior"> <div id="intro" class="interior"> <a href="https://nodejs.org/" title="Go back to the home page"> Node.js </a> </div> <ul> <li><a href="https://nodejs.org/api/documentation.html" class="nav-documentation">About these Docs</a></li> <li><a href="https://nodejs.org/api/synopsis.html" class="nav-synopsis">Usage & Example</a></li> </ul> <div class="line"></div> <ul> <li><a href="https://nodejs.org/api/assert.html" class="nav-assert">Assertion Testing</a></li> <li><a href="https://nodejs.org/api/async_hooks.html" class="nav-async_hooks">Async Hooks</a></li> <li><a href="https://nodejs.org/api/buffer.html" class="nav-buffer">Buffer</a></li> <li><a href="https://nodejs.org/api/addons.html" class="nav-addons">C++ Addons</a></li> <li><a href="https://nodejs.org/api/n-api.html" class="nav-n-api">C/C++ Addons - N-API</a></li> <li><a href="https://nodejs.org/api/child_process.html" class="nav-child_process">Child Processes</a></li> <li><a href="https://nodejs.org/api/cluster.html" class="nav-cluster">Cluster</a></li> <li><a href="https://nodejs.org/api/cli.html" class="nav-cli">Command Line Options</a></li> <li><a href="https://nodejs.org/api/console.html" class="nav-console">Console</a></li> <li><a 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</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-v12.x/api/process.html">12.x</a></li> <li><a href="https://nodejs.org/docs/latest-v11.x/api/process.html">11.x</a></li> <li><a href="https://nodejs.org/docs/latest-v10.x/api/process.html">10.x <b>LTS</b></a></li> <li><a href="https://nodejs.org/docs/latest-v9.x/api/process.html">9.x</a></li> <li><a href="https://nodejs.org/docs/latest-v8.x/api/process.html">8.x <b>LTS</b></a></li> <li><a href="https://nodejs.org/docs/latest-v7.x/api/process.html">7.x</a></li> <li><a href="https://nodejs.org/docs/latest-v6.x/api/process.html">6.x</a></li> <li><a href="https://nodejs.org/docs/latest-v5.x/api/process.html">5.x</a></li> <li><a href="https://nodejs.org/docs/latest-v4.x/api/process.html">4.x</a></li> <li><a href="https://nodejs.org/docs/latest-v0.12.x/api/process.html">0.12.x</a></li> <li><a href="https://nodejs.org/docs/latest-v0.10.x/api/process.html">0.10.x</a></li></ol> </li> <li class="edit_on_github"><a href="https://github.com/nodejs/node/edit/master/doc/api/process.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"></path></svg></span>Edit on GitHub</a></li> </ul> </div> <hr> </header> <div id="toc"> <h2>Table of Contents</h2> <ul> <li> <p><a href="#process_process">Process</a></p> <ul> <li> <p><a href="#process_process_events">Process Events</a></p> <ul> <li><a href="#process_event_beforeexit">Event: 'beforeExit'</a></li> <li><a href="#process_event_disconnect">Event: 'disconnect'</a></li> <li><a href="#process_event_exit">Event: 'exit'</a></li> <li><a href="#process_event_message">Event: 'message'</a></li> <li><a href="#process_event_multipleresolves">Event: 'multipleResolves'</a></li> <li><a href="#process_event_rejectionhandled">Event: 'rejectionHandled'</a></li> <li> <p><a href="#process_event_uncaughtexception">Event: 'uncaughtException'</a></p> <ul> <li><a href="#process_warning_using_uncaughtexception_correctly">Warning: Using <code>'uncaughtException'</code> correctly</a></li> </ul> </li> <li><a href="#process_event_unhandledrejection">Event: 'unhandledRejection'</a></li> <li> <p><a href="#process_event_warning">Event: 'warning'</a></p> <ul> <li><a href="#process_emitting_custom_warnings">Emitting custom warnings</a></li> </ul> </li> <li><a href="#process_signal_events">Signal Events</a></li> </ul> </li> <li><a href="#process_process_abort">process.abort()</a></li> <li><a href="#process_process_allowednodeenvironmentflags">process.allowedNodeEnvironmentFlags</a></li> <li><a href="#process_process_arch">process.arch</a></li> <li><a href="#process_process_argv">process.argv</a></li> <li><a href="#process_process_argv0">process.argv0</a></li> <li><a href="#process_process_channel">process.channel</a></li> <li><a href="#process_process_chdir_directory">process.chdir(directory)</a></li> <li><a href="#process_process_config">process.config</a></li> <li><a href="#process_process_connected">process.connected</a></li> <li><a href="#process_process_cpuusage_previousvalue">process.cpuUsage([previousValue])</a></li> <li><a href="#process_process_cwd">process.cwd()</a></li> <li><a href="#process_process_debugport">process.debugPort</a></li> <li><a href="#process_process_disconnect">process.disconnect()</a></li> <li><a href="#process_process_dlopen_module_filename_flags">process.dlopen(module, filename[, flags])</a></li> <li><a href="#process_process_emitwarning_warning_options">process.emitWarning(warning[, options])</a></li> <li> <p><a href="#process_process_emitwarning_warning_type_code_ctor">process.emitWarning(warning[, type[, code]][, ctor])</a></p> <ul> <li><a href="#process_avoiding_duplicate_warnings">Avoiding duplicate warnings</a></li> </ul> </li> <li><a href="#process_process_env">process.env</a></li> <li><a href="#process_process_execargv">process.execArgv</a></li> <li><a href="#process_process_execpath">process.execPath</a></li> <li><a href="#process_process_exit_code">process.exit([code])</a></li> <li><a href="#process_process_exitcode">process.exitCode</a></li> <li><a href="#process_process_getegid">process.getegid()</a></li> <li><a href="#process_process_geteuid">process.geteuid()</a></li> <li><a href="#process_process_getgid">process.getgid()</a></li> <li><a href="#process_process_getgroups">process.getgroups()</a></li> <li><a href="#process_process_getuid">process.getuid()</a></li> <li><a href="#process_process_hasuncaughtexceptioncapturecallback">process.hasUncaughtExceptionCaptureCallback()</a></li> <li><a href="#process_process_hrtime_time">process.hrtime([time])</a></li> <li><a href="#process_process_hrtime_bigint">process.hrtime.bigint()</a></li> <li><a href="#process_process_initgroups_user_extragroup">process.initgroups(user, extraGroup)</a></li> <li><a href="#process_process_kill_pid_signal">process.kill(pid[, signal])</a></li> <li><a href="#process_process_mainmodule">process.mainModule</a></li> <li><a href="#process_process_memoryusage">process.memoryUsage()</a></li> <li><a href="#process_process_nexttick_callback_args">process.nextTick(callback[, ...args])</a></li> <li><a href="#process_process_nodeprecation">process.noDeprecation</a></li> <li><a href="#process_process_pid">process.pid</a></li> <li><a href="#process_process_platform">process.platform</a></li> <li><a href="#process_process_ppid">process.ppid</a></li> <li><a href="#process_process_release">process.release</a></li> <li> <p><span class="stability_1"><a href="#process_process_report">process.report</a></span></p> <ul> <li><span class="stability_1"><a href="#process_process_report_directory">process.report.directory</a></span></li> <li><span class="stability_1"><a href="#process_process_report_filename">process.report.filename</a></span></li> <li><span class="stability_1"><a href="#process_process_report_getreport_err">process.report.getReport([err])</a></span></li> <li><span class="stability_1"><a href="#process_process_report_reportonfatalerror">process.report.reportOnFatalError</a></span></li> <li><span class="stability_1"><a href="#process_process_report_reportonsignal">process.report.reportOnSignal</a></span></li> <li><span class="stability_1"><a href="#process_process_report_reportonuncaughtexception">process.report.reportOnUncaughtException</a></span></li> <li><span class="stability_1"><a href="#process_process_report_signal">process.report.signal</a></span></li> <li><span class="stability_1"><a href="#process_process_report_writereport_filename_err">process.report.writeReport([filename][, err])</a></span></li> </ul> </li> <li><a href="#process_process_resourceusage">process.resourceUsage()</a></li> <li><a href="#process_process_send_message_sendhandle_options_callback">process.send(message[, sendHandle[, options]][, callback])</a></li> <li><a href="#process_process_setegid_id">process.setegid(id)</a></li> <li><a href="#process_process_seteuid_id">process.seteuid(id)</a></li> <li><a href="#process_process_setgid_id">process.setgid(id)</a></li> <li><a href="#process_process_setgroups_groups">process.setgroups(groups)</a></li> <li><a href="#process_process_setuid_id">process.setuid(id)</a></li> <li><a href="#process_process_setuncaughtexceptioncapturecallback_fn">process.setUncaughtExceptionCaptureCallback(fn)</a></li> <li><a href="#process_process_stderr">process.stderr</a></li> <li><a href="#process_process_stdin">process.stdin</a></li> <li> <p><a href="#process_process_stdout">process.stdout</a></p> <ul> <li><a href="#process_a_note_on_process_i_o">A note on process I/O</a></li> </ul> </li> <li><a href="#process_process_throwdeprecation">process.throwDeprecation</a></li> <li><a href="#process_process_title">process.title</a></li> <li><a href="#process_process_tracedeprecation">process.traceDeprecation</a></li> <li><a href="#process_process_umask_mask">process.umask([mask])</a></li> <li><a href="#process_process_uptime">process.uptime()</a></li> <li><a href="#process_process_version">process.version</a></li> <li><a href="#process_process_versions">process.versions</a></li> <li><a href="#process_exit_codes">Exit Codes</a></li> </ul> </li> </ul> </div> <div id="apicontent"> <h1>Process<span><a class="mark" href="#process_process" id="process_process">#</a></span></h1> <p>The <code>process</code> object is a <code>global</code> that provides information about, and control over, the current Node.js process. As a global, it is always available to Node.js applications without using <code>require()</code>. It can also be explicitly accessed using <code>require()</code>:</p> <pre><code class="language-js">const process = require('process'); </code></pre> <h2>Process Events<span><a class="mark" href="#process_process_events" id="process_process_events">#</a></span></h2> <p>The <code>process</code> object is an instance of <a href="https://nodejs.org/api/events.html#events_class_eventemitter"><code>EventEmitter</code></a>.</p> <h3>Event: 'beforeExit'<span><a class="mark" href="#process_event_beforeexit" id="process_event_beforeexit">#</a></span></h3> <div class="api_metadata"> <span>Added in: v0.11.12</span> </div> <p>The <code>'beforeExit'</code> event is emitted when Node.js empties its event loop and has no additional work to schedule. Normally, the Node.js process will exit when there is no work scheduled, but a listener registered on the <code>'beforeExit'</code> event can make asynchronous calls, and thereby cause the Node.js process to continue.</p> <p>The listener callback function is invoked with the value of <a href="#process_process_exitcode"><code>process.exitCode</code></a> passed as the only argument.</p> <p>The <code>'beforeExit'</code> event is <em>not</em> emitted for conditions causing explicit termination, such as calling <a href="#process_process_exit_code"><code>process.exit()</code></a> or uncaught exceptions.</p> <p>The <code>'beforeExit'</code> should <em>not</em> be used as an alternative to the <code>'exit'</code> event unless the intention is to schedule additional work.</p> <pre><code class="language-js">process.on('beforeExit', (code) => { console.log('Process beforeExit event with code: ', code); }); process.on('exit', (code) => { console.log('Process exit event with code: ', code); }); console.log('This message is displayed first.'); // Prints: // This message is displayed first. // Process beforeExit event with code: 0 // Process exit event with code: 0 </code></pre> <h3>Event: 'disconnect'<span><a class="mark" href="#process_event_disconnect" id="process_event_disconnect">#</a></span></h3> <div class="api_metadata"> <span>Added in: v0.7.7</span> </div> <p>If the Node.js process is spawned with an IPC channel (see the <a href="https://nodejs.org/api/child_process.html">Child Process</a> and <a href="https://nodejs.org/api/cluster.html">Cluster</a> documentation), the <code>'disconnect'</code> event will be emitted when the IPC channel is closed.</p> <h3>Event: 'exit'<span><a class="mark" href="#process_event_exit" id="process_event_exit">#</a></span></h3> <div class="api_metadata"> <span>Added in: v0.1.7</span> </div> <ul> <li><code>code</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> </ul> <p>The <code>'exit'</code> event is emitted when the Node.js process is about to exit as a result of either:</p> <ul> <li>The <code>process.exit()</code> method being called explicitly;</li> <li>The Node.js event loop no longer having any additional work to perform.</li> </ul> <p>There is no way to prevent the exiting of the event loop at this point, and once all <code>'exit'</code> listeners have finished running the Node.js process will terminate.</p> <p>The listener callback function is invoked with the exit code specified either by the <a href="#process_process_exitcode"><code>process.exitCode</code></a> property, or the <code>exitCode</code> argument passed to the <a href="#process_process_exit_code"><code>process.exit()</code></a> method.</p> <pre><code class="language-js">process.on('exit', (code) => { console.log(`About to exit with code: ${code}`); }); </code></pre> <p>Listener functions <strong>must</strong> only perform <strong>synchronous</strong> operations. The Node.js process will exit immediately after calling the <code>'exit'</code> event listeners causing any additional work still queued in the event loop to be abandoned. In the following example, for instance, the timeout will never occur:</p> <pre><code class="language-js">process.on('exit', (code) => { setTimeout(() => { console.log('This will not run'); }, 0); }); </code></pre> <h3>Event: 'message'<span><a class="mark" href="#process_event_message" id="process_event_message">#</a></span></h3> <div class="api_metadata"> <span>Added in: v0.5.10</span> </div> <ul> <li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> | <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#Number_type" class="type"><number></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Null_type" class="type"><null></a> a parsed JSON object or a serializable primitive value.</li> <li><code>sendHandle</code> <a href="https://nodejs.org/api/net.html#net_class_net_server" class="type"><net.Server></a> | <a href="https://nodejs.org/api/net.html#net_class_net_socket" class="type"><net.Socket></a> a <a href="https://nodejs.org/api/net.html#net_class_net_server"><code>net.Server</code></a> or <a href="https://nodejs.org/api/net.html#net_class_net_socket"><code>net.Socket</code></a> object, or undefined.</li> </ul> <p>If the Node.js process is spawned with an IPC channel (see the <a href="https://nodejs.org/api/child_process.html">Child Process</a> and <a href="https://nodejs.org/api/cluster.html">Cluster</a> documentation), the <code>'message'</code> event is emitted whenever a message sent by a parent process using <a href="https://nodejs.org/api/child_process.html#child_process_subprocess_send_message_sendhandle_options_callback"><code>childprocess.send()</code></a> is received by the child process.</p> <p>The message goes through serialization and parsing. The resulting message might not be the same as what is originally sent.</p> <h3>Event: 'multipleResolves'<span><a class="mark" href="#process_event_multipleresolves" id="process_event_multipleresolves">#</a></span></h3> <div class="api_metadata"> <span>Added in: v10.12.0</span> </div> <ul> <li><code>type</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The resolution type. One of <code>'resolve'</code> or <code>'reject'</code>.</li> <li><code>promise</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type"><Promise></a> The promise that resolved or rejected more than once.</li> <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 with which the promise was either resolved or rejected after the original resolve.</li> </ul> <p>The <code>'multipleResolves'</code> event is emitted whenever a <code>Promise</code> has been either:</p> <ul> <li>Resolved more than once.</li> <li>Rejected more than once.</li> <li>Rejected after resolve.</li> <li>Resolved after reject.</li> </ul> <p>This is useful for tracking potential errors in an application while using the <code>Promise</code> constructor, as multiple resolutions are silently swallowed. However, the occurrence of this event does not necessarily indicate an error. For example, <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/race"><code>Promise.race()</code></a> can trigger a <code>'multipleResolves'</code> event.</p> <pre><code class="language-js">process.on('multipleResolves', (type, promise, reason) => { console.error(type, promise, reason); setImmediate(() => process.exit(1)); }); async function main() { try { return await new Promise((resolve, reject) => { resolve('First call'); resolve('Swallowed resolve'); reject(new Error('Swallowed reject')); }); } catch { throw new Error('Failed'); } } main().then(console.log); // resolve: Promise { 'First call' } 'Swallowed resolve' // reject: Promise { 'First call' } Error: Swallowed reject // at Promise (*) // at new Promise (<anonymous>) // at main (*) // First call </code></pre> <h3>Event: 'rejectionHandled'<span><a class="mark" href="#process_event_rejectionhandled" id="process_event_rejectionhandled">#</a></span></h3> <div class="api_metadata"> <span>Added in: v1.4.1</span> </div> <ul> <li><code>promise</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type"><Promise></a> The late handled promise.</li> </ul> <p>The <code>'rejectionHandled'</code> event is emitted whenever a <code>Promise</code> has been rejected and an error handler was attached to it (using <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/catch"><code>promise.catch()</code></a>, for example) later than one turn of the Node.js event loop.</p> <p>The <code>Promise</code> object would have previously been emitted in an <code>'unhandledRejection'</code> event, but during the course of processing gained a rejection handler.</p> <p>There is no notion of a top level for a <code>Promise</code> chain at which rejections can always be handled. Being inherently asynchronous in nature, a <code>Promise</code> rejection can be handled at a future point in time — possibly much later than the event loop turn it takes for the <code>'unhandledRejection'</code> event to be emitted.</p> <p>Another way of stating this is that, unlike in synchronous code where there is an ever-growing list of unhandled exceptions, with Promises there can be a growing-and-shrinking list of unhandled rejections.</p> <p>In synchronous code, the <code>'uncaughtException'</code> event is emitted when the list of unhandled exceptions grows.</p> <p>In asynchronous code, the <code>'unhandledRejection'</code> event is emitted when the list of unhandled rejections grows, and the <code>'rejectionHandled'</code> event is emitted when the list of unhandled rejections shrinks.</p> <pre><code class="language-js">const unhandledRejections = new Map(); process.on('unhandledRejection', (reason, promise) => { unhandledRejections.set(promise, reason); }); process.on('rejectionHandled', (promise) => { unhandledRejections.delete(promise); }); </code></pre> <p>In this example, the <code>unhandledRejections</code> <code>Map</code> will grow and shrink over time, reflecting rejections that start unhandled and then become handled. It is possible to record such errors in an error log, either periodically (which is likely best for long-running application) or upon process exit (which is likely most convenient for scripts).</p> <h3>Event: 'uncaughtException'<span><a class="mark" href="#process_event_uncaughtexception" id="process_event_uncaughtexception">#</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>v12.0.0</td> <td><p>Added the <code>origin</code> argument.</p></td></tr> <tr><td>v0.1.18</td> <td><p><span>Added in: v0.1.18</span></p></td></tr> </tbody></table> </details> </div> <ul> <li><code>err</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type"><Error></a> The uncaught exception.</li> <li><code>origin</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Indicates if the exception originates from an unhandled rejection or from synchronous errors. Can either be <code>'uncaughtException'</code> or <code>'unhandledRejection'</code>.</li> </ul> <p>The <code>'uncaughtException'</code> event is emitted when an uncaught JavaScript exception bubbles all the way back to the event loop. By default, Node.js handles such exceptions by printing the stack trace to <code>stderr</code> and exiting with code 1, overriding any previously set <a href="#process_process_exitcode"><code>process.exitCode</code></a>. Adding a handler for the <code>'uncaughtException'</code> event overrides this default behavior. Alternatively, change the <a href="#process_process_exitcode"><code>process.exitCode</code></a> in the <code>'uncaughtException'</code> handler which will result in the process exiting with the provided exit code. Otherwise, in the presence of such handler the process will exit with 0.</p> <pre><code class="language-js">process.on('uncaughtException', (err, origin) => { fs.writeSync( process.stderr.fd, `Caught exception: ${err}\n` + `Exception origin: ${origin}` ); }); setTimeout(() => { console.log('This will still run.'); }, 500); // Intentionally cause an exception, but don't catch it. nonexistentFunc(); console.log('This will not run.'); </code></pre> <h4>Warning: Using <code>'uncaughtException'</code> correctly<span><a class="mark" href="#process_warning_using_uncaughtexception_correctly" id="process_warning_using_uncaughtexception_correctly">#</a></span></h4> <p><code>'uncaughtException'</code> is a crude mechanism for exception handling intended to be used only as a last resort. The event <em>should not</em> be used as an equivalent to <code>On Error Resume Next</code>. Unhandled exceptions inherently mean that an application is in an undefined state. Attempting to resume application code without properly recovering from the exception can cause additional unforeseen and unpredictable issues.</p> <p>Exceptions thrown from within the event handler will not be caught. Instead the process will exit with a non-zero exit code and the stack trace will be printed. This is to avoid infinite recursion.</p> <p>Attempting to resume normally after an uncaught exception can be similar to pulling out of the power cord when upgrading a computer — nine out of ten times nothing happens - but the 10th time, the system becomes corrupted.</p> <p>The correct use of <code>'uncaughtException'</code> is to perform synchronous cleanup of allocated resources (e.g. file descriptors, handles, etc) before shutting down the process. <strong>It is not safe to resume normal operation after <code>'uncaughtException'</code>.</strong></p> <p>To restart a crashed application in a more reliable way, whether <code>'uncaughtException'</code> is emitted or not, an external monitor should be employed in a separate process to detect application failures and recover or restart as needed.</p> <h3>Event: 'unhandledRejection'<span><a class="mark" href="#process_event_unhandledrejection" id="process_event_unhandledrejection">#</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>v7.0.0</td> <td><p>Not handling <code>Promise</code> rejections is deprecated.</p></td></tr> <tr><td>v6.6.0</td> <td><p>Unhandled <code>Promise</code> rejections will now emit a process warning.</p></td></tr> <tr><td>v1.4.1</td> <td><p><span>Added in: v1.4.1</span></p></td></tr> </tbody></table> </details> </div> <ul> <li><code>reason</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type"><Error></a> | <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> The object with which the promise was rejected (typically an <a href="https://nodejs.org/api/errors.html#errors_class_error"><code>Error</code></a> object).</li> <li><code>promise</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type"><Promise></a> The rejected promise.</li> </ul> <p>The <code>'unhandledRejection'</code> event is emitted whenever a <code>Promise</code> is rejected and no error handler is attached to the promise within a turn of the event loop. When programming with Promises, exceptions are encapsulated as "rejected promises". Rejections can be caught and handled using <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/catch"><code>promise.catch()</code></a> and are propagated through a <code>Promise</code> chain. The <code>'unhandledRejection'</code> event is useful for detecting and keeping track of promises that were rejected whose rejections have not yet been handled.</p> <pre><code class="language-js">process.on('unhandledRejection', (reason, promise) => { console.log('Unhandled Rejection at:', promise, 'reason:', reason); // Application specific logging, throwing an error, or other logic here }); somePromise.then((res) => { return reportToUser(JSON.pasre(res)); // Note the typo (`pasre`) }); // No `.catch()` or `.then()` </code></pre> <p>The following will also trigger the <code>'unhandledRejection'</code> event to be emitted:</p> <pre><code class="language-js">function SomeResource() { // Initially set the loaded status to a rejected promise this.loaded = Promise.reject(new Error('Resource not yet loaded!')); } const resource = new SomeResource(); // no .catch or .then on resource.loaded for at least a turn </code></pre> <p>In this example case, it is possible to track the rejection as a developer error as would typically be the case for other <code>'unhandledRejection'</code> events. To address such failures, a non-operational <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/catch"><code>.catch(() => { })</code></a> handler may be attached to <code>resource.loaded</code>, which would prevent the <code>'unhandledRejection'</code> event from being emitted.</p> <h3>Event: 'warning'<span><a class="mark" href="#process_event_warning" id="process_event_warning">#</a></span></h3> <div class="api_metadata"> <span>Added in: v6.0.0</span> </div> <ul> <li> <p><code>warning</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error" class="type"><Error></a> Key properties of the warning are:</p> <ul> <li><code>name</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The name of the warning. <strong>Default:</strong> <code>'Warning'</code>.</li> <li><code>message</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> A system-provided description of the warning.</li> <li><code>stack</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> A stack trace to the location in the code where the warning was issued.</li> </ul> </li> </ul> <p>The <code>'warning'</code> event is emitted whenever Node.js emits a process warning.</p> <p>A process warning is similar to an error in that it describes exceptional conditions that are being brought to the user's attention. However, warnings are not part of the normal Node.js and JavaScript error handling flow. Node.js can emit warnings whenever it detects bad coding practices that could lead to sub-optimal application performance, bugs, or security vulnerabilities.</p> <pre><code class="language-js">process.on('warning', (warning) => { console.warn(warning.name); // Print the warning name console.warn(warning.message); // Print the warning message console.warn(warning.stack); // Print the stack trace }); </code></pre> <p>By default, Node.js will print process warnings to <code>stderr</code>. The <code>--no-warnings</code> command-line option can be used to suppress the default console output but the <code>'warning'</code> event will still be emitted by the <code>process</code> object.</p> <p>The following example illustrates the warning that is printed to <code>stderr</code> when too