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133<li><a href="#class-timeout">Class: <code>Timeout</code></a> 134<ul> 135<li><span class="stability_3"><a href="#timeoutclose"><code>timeout.close()</code></a></span></li> 136<li><a href="#timeouthasref"><code>timeout.hasRef()</code></a></li> 137<li><a href="#timeoutref"><code>timeout.ref()</code></a></li> 138<li><a href="#timeoutrefresh"><code>timeout.refresh()</code></a></li> 139<li><a href="#timeoutunref"><code>timeout.unref()</code></a></li> 140<li><a href="#timeoutsymboltoprimitive"><code>timeout[Symbol.toPrimitive]()</code></a></li> 141<li><span class="stability_1"><a href="#timeoutsymboldispose"><code>timeout[Symbol.dispose]()</code></a></span></li> 142</ul> 143</li> 144<li><a href="#scheduling-timers">Scheduling timers</a> 145<ul> 146<li><a href="#setimmediatecallback-args"><code>setImmediate(callback[, ...args])</code></a></li> 147<li><a href="#setintervalcallback-delay-args"><code>setInterval(callback[, delay[, ...args]])</code></a></li> 148<li><a href="#settimeoutcallback-delay-args"><code>setTimeout(callback[, delay[, ...args]])</code></a></li> 149</ul> 150</li> 151<li><a href="#cancelling-timers">Cancelling timers</a> 152<ul> 153<li><a href="#clearimmediateimmediate"><code>clearImmediate(immediate)</code></a></li> 154<li><a href="#clearintervaltimeout"><code>clearInterval(timeout)</code></a></li> 155<li><a href="#cleartimeouttimeout"><code>clearTimeout(timeout)</code></a></li> 156</ul> 157</li> 158<li><a href="#timers-promises-api">Timers Promises API</a> 159<ul> 160<li><a href="#timerspromisessettimeoutdelay-value-options"><code>timersPromises.setTimeout([delay[, value[, options]]])</code></a></li> 161<li><a href="#timerspromisessetimmediatevalue-options"><code>timersPromises.setImmediate([value[, options]])</code></a></li> 162<li><a href="#timerspromisessetintervaldelay-value-options"><code>timersPromises.setInterval([delay[, value[, options]]])</code></a></li> 163<li><span class="stability_1"><a href="#timerspromisesschedulerwaitdelay-options"><code>timersPromises.scheduler.wait(delay[, options])</code></a></span></li> 164<li><span class="stability_1"><a href="#timerspromisesscheduleryield"><code>timersPromises.scheduler.yield()</code></a></span></li> 165</ul> 166</li> 167</ul> 168</li> 169</ul></div></div> 170 </li> 171 172 173 <li class="picker-header"> 174 <a href="#"> 175 <span class="collapsed-arrow">►</span><span class="expanded-arrow">▼</span> 176 Index 177 </a> 178 179 <div class="picker"><ul> 180<li><a href="documentation.html" class="nav-documentation">About this documentation</a></li> 181<li><a href="synopsis.html" class="nav-synopsis">Usage and example</a></li> 182 183 <li> 184 <a href="index.html">Index</a> 185 </li> 186 </ul> 187 188<hr class="line"> 189<ul> 190<li><a href="assert.html" class="nav-assert">Assertion testing</a></li> 191<li><a href="async_context.html" class="nav-async_context">Asynchronous context tracking</a></li> 192<li><a 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href="https://nodejs.org/docs/latest-v16.x/api/timers.html">16.x</a></li> 269<li><a href="https://nodejs.org/docs/latest-v15.x/api/timers.html">15.x</a></li> 270<li><a href="https://nodejs.org/docs/latest-v14.x/api/timers.html">14.x</a></li> 271<li><a href="https://nodejs.org/docs/latest-v13.x/api/timers.html">13.x</a></li> 272<li><a href="https://nodejs.org/docs/latest-v12.x/api/timers.html">12.x</a></li> 273<li><a href="https://nodejs.org/docs/latest-v11.x/api/timers.html">11.x</a></li> 274<li><a href="https://nodejs.org/docs/latest-v10.x/api/timers.html">10.x</a></li> 275<li><a href="https://nodejs.org/docs/latest-v9.x/api/timers.html">9.x</a></li> 276<li><a href="https://nodejs.org/docs/latest-v8.x/api/timers.html">8.x</a></li> 277<li><a href="https://nodejs.org/docs/latest-v7.x/api/timers.html">7.x</a></li> 278<li><a href="https://nodejs.org/docs/latest-v6.x/api/timers.html">6.x</a></li> 279<li><a href="https://nodejs.org/docs/latest-v5.x/api/timers.html">5.x</a></li> 280<li><a href="https://nodejs.org/docs/latest-v4.x/api/timers.html">4.x</a></li> 281<li><a href="https://nodejs.org/docs/latest-v0.12.x/api/timers.html">0.12.x</a></li> 282<li><a href="https://nodejs.org/docs/latest-v0.10.x/api/timers.html">0.10.x</a></li></ol></div> 283 </li> 284 285 <li class="picker-header"> 286 <a href="#"> 287 <span class="collapsed-arrow">►</span><span class="expanded-arrow">▼</span> 288 Options 289 </a> 290 291 <div class="picker"> 292 <ul> 293 <li> 294 <a href="all.html">View on single page</a> 295 </li> 296 <li> 297 <a href="timers.json">View as JSON</a> 298 </li> 299 <li class="edit_on_github"><a href="https://github.com/nodejs/node/edit/main/doc/api/timers.md">Edit on GitHub</a></li> 300 </ul> 301 </div> 302 </li> 303 </ul> 304 </div> 305 <hr> 306 </header> 307 308 <details id="toc" open><summary>Table of contents</summary><ul> 309<li><span class="stability_2"><a href="#timers">Timers</a></span> 310<ul> 311<li><a href="#class-immediate">Class: <code>Immediate</code></a> 312<ul> 313<li><a href="#immediatehasref"><code>immediate.hasRef()</code></a></li> 314<li><a href="#immediateref"><code>immediate.ref()</code></a></li> 315<li><a href="#immediateunref"><code>immediate.unref()</code></a></li> 316<li><span class="stability_1"><a href="#immediatesymboldispose"><code>immediate[Symbol.dispose]()</code></a></span></li> 317</ul> 318</li> 319<li><a href="#class-timeout">Class: <code>Timeout</code></a> 320<ul> 321<li><span class="stability_3"><a href="#timeoutclose"><code>timeout.close()</code></a></span></li> 322<li><a href="#timeouthasref"><code>timeout.hasRef()</code></a></li> 323<li><a href="#timeoutref"><code>timeout.ref()</code></a></li> 324<li><a href="#timeoutrefresh"><code>timeout.refresh()</code></a></li> 325<li><a href="#timeoutunref"><code>timeout.unref()</code></a></li> 326<li><a href="#timeoutsymboltoprimitive"><code>timeout[Symbol.toPrimitive]()</code></a></li> 327<li><span class="stability_1"><a href="#timeoutsymboldispose"><code>timeout[Symbol.dispose]()</code></a></span></li> 328</ul> 329</li> 330<li><a href="#scheduling-timers">Scheduling timers</a> 331<ul> 332<li><a href="#setimmediatecallback-args"><code>setImmediate(callback[, ...args])</code></a></li> 333<li><a href="#setintervalcallback-delay-args"><code>setInterval(callback[, delay[, ...args]])</code></a></li> 334<li><a href="#settimeoutcallback-delay-args"><code>setTimeout(callback[, delay[, ...args]])</code></a></li> 335</ul> 336</li> 337<li><a href="#cancelling-timers">Cancelling timers</a> 338<ul> 339<li><a href="#clearimmediateimmediate"><code>clearImmediate(immediate)</code></a></li> 340<li><a href="#clearintervaltimeout"><code>clearInterval(timeout)</code></a></li> 341<li><a href="#cleartimeouttimeout"><code>clearTimeout(timeout)</code></a></li> 342</ul> 343</li> 344<li><a href="#timers-promises-api">Timers Promises API</a> 345<ul> 346<li><a href="#timerspromisessettimeoutdelay-value-options"><code>timersPromises.setTimeout([delay[, value[, options]]])</code></a></li> 347<li><a href="#timerspromisessetimmediatevalue-options"><code>timersPromises.setImmediate([value[, options]])</code></a></li> 348<li><a href="#timerspromisessetintervaldelay-value-options"><code>timersPromises.setInterval([delay[, value[, options]]])</code></a></li> 349<li><span class="stability_1"><a href="#timerspromisesschedulerwaitdelay-options"><code>timersPromises.scheduler.wait(delay[, options])</code></a></span></li> 350<li><span class="stability_1"><a href="#timerspromisesscheduleryield"><code>timersPromises.scheduler.yield()</code></a></span></li> 351</ul> 352</li> 353</ul> 354</li> 355</ul></details> 356 357 <div id="apicontent"> 358 <h2>Timers<span><a class="mark" href="#timers" id="timers">#</a></span><a aria-hidden="true" class="legacy" id="timers_timers"></a></h2> 359 360<p></p><div class="api_stability api_stability_2"><a href="documentation.html#stability-index">Stability: 2</a> - Stable</div><p></p> 361<p><strong>Source Code:</strong> <a href="https://github.com/nodejs/node/blob/v18.20.1/lib/timers.js">lib/timers.js</a></p> 362<p>The <code>timer</code> module exposes a global API for scheduling functions to 363be called at some future period of time. Because the timer functions are 364globals, there is no need to call <code>require('node:timers')</code> to use the API.</p> 365<p>The timer functions within Node.js implement a similar API as the timers API 366provided by Web Browsers but use a different internal implementation that is 367built around the Node.js <a href="https://nodejs.org/en/docs/guides/event-loop-timers-and-nexttick/#setimmediate-vs-settimeout">Event Loop</a>.</p> 368<section><h3>Class: <code>Immediate</code><span><a class="mark" href="#class-immediate" id="class-immediate">#</a></span><a aria-hidden="true" class="legacy" id="timers_class_immediate"></a></h3> 369<p>This object is created internally and is returned from <a href="#setimmediatecallback-args"><code>setImmediate()</code></a>. It 370can be passed to <a href="#clearimmediateimmediate"><code>clearImmediate()</code></a> in order to cancel the scheduled 371actions.</p> 372<p>By default, when an immediate is scheduled, the Node.js event loop will continue 373running as long as the immediate is active. The <code>Immediate</code> object returned by 374<a href="#setimmediatecallback-args"><code>setImmediate()</code></a> exports both <code>immediate.ref()</code> and <code>immediate.unref()</code> 375functions that can be used to control this default behavior.</p> 376<h4><code>immediate.hasRef()</code><span><a class="mark" href="#immediatehasref" id="immediatehasref">#</a></span><a aria-hidden="true" class="legacy" id="timers_immediate_hasref"></a></h4> 377<div class="api_metadata"> 378<span>Added in: v11.0.0</span> 379</div> 380<ul> 381<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a></li> 382</ul> 383<p>If true, the <code>Immediate</code> object will keep the Node.js event loop active.</p> 384<h4><code>immediate.ref()</code><span><a class="mark" href="#immediateref" id="immediateref">#</a></span><a aria-hidden="true" class="legacy" id="timers_immediate_ref"></a></h4> 385<div class="api_metadata"> 386<span>Added in: v9.7.0</span> 387</div> 388<ul> 389<li>Returns: <a href="timers.html#class-immediate" class="type"><Immediate></a> a reference to <code>immediate</code></li> 390</ul> 391<p>When called, requests that the Node.js event loop <em>not</em> exit so long as the 392<code>Immediate</code> is active. Calling <code>immediate.ref()</code> multiple times will have no 393effect.</p> 394<p>By default, all <code>Immediate</code> objects are "ref'ed", making it normally unnecessary 395to call <code>immediate.ref()</code> unless <code>immediate.unref()</code> had been called previously.</p> 396<h4><code>immediate.unref()</code><span><a class="mark" href="#immediateunref" id="immediateunref">#</a></span><a aria-hidden="true" class="legacy" id="timers_immediate_unref"></a></h4> 397<div class="api_metadata"> 398<span>Added in: v9.7.0</span> 399</div> 400<ul> 401<li>Returns: <a href="timers.html#class-immediate" class="type"><Immediate></a> a reference to <code>immediate</code></li> 402</ul> 403<p>When called, the active <code>Immediate</code> object will not require the Node.js event 404loop to remain active. If there is no other activity keeping the event loop 405running, the process may exit before the <code>Immediate</code> object's callback is 406invoked. Calling <code>immediate.unref()</code> multiple times will have no effect.</p> 407<h4><code>immediate[Symbol.dispose]()</code><span><a class="mark" href="#immediatesymboldispose" id="immediatesymboldispose">#</a></span><a aria-hidden="true" class="legacy" id="timers_immediate_symbol_dispose"></a></h4> 408<div class="api_metadata"> 409<span>Added in: v18.18.0</span> 410</div> 411<p></p><div class="api_stability api_stability_1"><a href="documentation.html#stability-index">Stability: 1</a> - Experimental</div><p></p> 412<p>Cancels the immediate. This is similar to calling <code>clearImmediate()</code>.</p> 413</section><section><h3>Class: <code>Timeout</code><span><a class="mark" href="#class-timeout" id="class-timeout">#</a></span><a aria-hidden="true" class="legacy" id="timers_class_timeout"></a></h3> 414<p>This object is created internally and is returned from <a href="#settimeoutcallback-delay-args"><code>setTimeout()</code></a> and 415<a href="#setintervalcallback-delay-args"><code>setInterval()</code></a>. It can be passed to either <a href="#cleartimeouttimeout"><code>clearTimeout()</code></a> or 416<a href="#clearintervaltimeout"><code>clearInterval()</code></a> in order to cancel the scheduled actions.</p> 417<p>By default, when a timer is scheduled using either <a href="#settimeoutcallback-delay-args"><code>setTimeout()</code></a> or 418<a href="#setintervalcallback-delay-args"><code>setInterval()</code></a>, the Node.js event loop will continue running as long as the 419timer is active. Each of the <code>Timeout</code> objects returned by these functions 420export both <code>timeout.ref()</code> and <code>timeout.unref()</code> functions that can be used to 421control this default behavior.</p> 422<h4><code>timeout.close()</code><span><a class="mark" href="#timeoutclose" id="timeoutclose">#</a></span><a aria-hidden="true" class="legacy" id="timers_timeout_close"></a></h4> 423<div class="api_metadata"> 424<span>Added in: v0.9.1</span> 425</div> 426<p></p><div class="api_stability api_stability_3"><a href="documentation.html#stability-index">Stability: 3</a> - Legacy: Use <a href="#cleartimeouttimeout"><code>clearTimeout()</code></a> instead.</div><p></p> 427<ul> 428<li>Returns: <a href="timers.html#class-timeout" class="type"><Timeout></a> a reference to <code>timeout</code></li> 429</ul> 430<p>Cancels the timeout.</p> 431<h4><code>timeout.hasRef()</code><span><a class="mark" href="#timeouthasref" id="timeouthasref">#</a></span><a aria-hidden="true" class="legacy" id="timers_timeout_hasref"></a></h4> 432<div class="api_metadata"> 433<span>Added in: v11.0.0</span> 434</div> 435<ul> 436<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a></li> 437</ul> 438<p>If true, the <code>Timeout</code> object will keep the Node.js event loop active.</p> 439<h4><code>timeout.ref()</code><span><a class="mark" href="#timeoutref" id="timeoutref">#</a></span><a aria-hidden="true" class="legacy" id="timers_timeout_ref"></a></h4> 440<div class="api_metadata"> 441<span>Added in: v0.9.1</span> 442</div> 443<ul> 444<li>Returns: <a href="timers.html#class-timeout" class="type"><Timeout></a> a reference to <code>timeout</code></li> 445</ul> 446<p>When called, requests that the Node.js event loop <em>not</em> exit so long as the 447<code>Timeout</code> is active. Calling <code>timeout.ref()</code> multiple times will have no effect.</p> 448<p>By default, all <code>Timeout</code> objects are "ref'ed", making it normally unnecessary 449to call <code>timeout.ref()</code> unless <code>timeout.unref()</code> had been called previously.</p> 450<h4><code>timeout.refresh()</code><span><a class="mark" href="#timeoutrefresh" id="timeoutrefresh">#</a></span><a aria-hidden="true" class="legacy" id="timers_timeout_refresh"></a></h4> 451<div class="api_metadata"> 452<span>Added in: v10.2.0</span> 453</div> 454<ul> 455<li>Returns: <a href="timers.html#class-timeout" class="type"><Timeout></a> a reference to <code>timeout</code></li> 456</ul> 457<p>Sets the timer's start time to the current time, and reschedules the timer to 458call its callback at the previously specified duration adjusted to the current 459time. This is useful for refreshing a timer without allocating a new 460JavaScript object.</p> 461<p>Using this on a timer that has already called its callback will reactivate the 462timer.</p> 463<h4><code>timeout.unref()</code><span><a class="mark" href="#timeoutunref" id="timeoutunref">#</a></span><a aria-hidden="true" class="legacy" id="timers_timeout_unref"></a></h4> 464<div class="api_metadata"> 465<span>Added in: v0.9.1</span> 466</div> 467<ul> 468<li>Returns: <a href="timers.html#class-timeout" class="type"><Timeout></a> a reference to <code>timeout</code></li> 469</ul> 470<p>When called, the active <code>Timeout</code> object will not require the Node.js event loop 471to remain active. If there is no other activity keeping the event loop running, 472the process may exit before the <code>Timeout</code> object's callback is invoked. Calling 473<code>timeout.unref()</code> multiple times will have no effect.</p> 474<h4><code>timeout[Symbol.toPrimitive]()</code><span><a class="mark" href="#timeoutsymboltoprimitive" id="timeoutsymboltoprimitive">#</a></span><a aria-hidden="true" class="legacy" id="timers_timeout_symbol_toprimitive"></a></h4> 475<div class="api_metadata"> 476<span>Added in: v14.9.0, v12.19.0</span> 477</div> 478<ul> 479<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> a number that can be used to reference this <code>timeout</code></li> 480</ul> 481<p>Coerce a <code>Timeout</code> to a primitive. The primitive can be used to 482clear the <code>Timeout</code>. The primitive can only be used in the 483same thread where the timeout was created. Therefore, to use it 484across <a href="worker_threads.html"><code>worker_threads</code></a> it must first be passed to the correct 485thread. This allows enhanced compatibility with browser 486<code>setTimeout()</code> and <code>setInterval()</code> implementations.</p> 487<h4><code>timeout[Symbol.dispose]()</code><span><a class="mark" href="#timeoutsymboldispose" id="timeoutsymboldispose">#</a></span><a aria-hidden="true" class="legacy" id="timers_timeout_symbol_dispose"></a></h4> 488<div class="api_metadata"> 489<span>Added in: v18.18.0</span> 490</div> 491<p></p><div class="api_stability api_stability_1"><a href="documentation.html#stability-index">Stability: 1</a> - Experimental</div><p></p> 492<p>Cancels the timeout.</p> 493</section><section><h3>Scheduling timers<span><a class="mark" href="#scheduling-timers" id="scheduling-timers">#</a></span><a aria-hidden="true" class="legacy" id="timers_scheduling_timers"></a></h3> 494<p>A timer in Node.js is an internal construct that calls a given function after 495a certain period of time. When a timer's function is called varies depending on 496which method was used to create the timer and what other work the Node.js 497event loop is doing.</p> 498<h4><code>setImmediate(callback[, ...args])</code><span><a class="mark" href="#setimmediatecallback-args" id="setimmediatecallback-args">#</a></span><a aria-hidden="true" class="legacy" id="timers_setimmediate_callback_args"></a></h4> 499<div class="api_metadata"> 500<details class="changelog"><summary>History</summary> 501<table> 502<tbody><tr><th>Version</th><th>Changes</th></tr> 503<tr><td>v18.0.0</td> 504<td><p>Passing an invalid callback to the <code>callback</code> argument now throws <code>ERR_INVALID_ARG_TYPE</code> instead of <code>ERR_INVALID_CALLBACK</code>.</p></td></tr> 505<tr><td>v0.9.1</td> 506<td><p><span>Added in: v0.9.1</span></p></td></tr> 507</tbody></table> 508</details> 509</div> 510<ul> 511<li><code>callback</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a> The function to call at the end of this turn of 512the Node.js <a href="https://nodejs.org/en/docs/guides/event-loop-timers-and-nexttick/#setimmediate-vs-settimeout">Event Loop</a></li> 513<li><code>...args</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> Optional arguments to pass when the <code>callback</code> is called.</li> 514<li>Returns: <a href="timers.html#class-immediate" class="type"><Immediate></a> for use with <a href="#clearimmediateimmediate"><code>clearImmediate()</code></a></li> 515</ul> 516<p>Schedules the "immediate" execution of the <code>callback</code> after I/O events' 517callbacks.</p> 518<p>When multiple calls to <code>setImmediate()</code> are made, the <code>callback</code> functions are 519queued for execution in the order in which they are created. The entire callback 520queue is processed every event loop iteration. If an immediate timer is queued 521from inside an executing callback, that timer will not be triggered until the 522next event loop iteration.</p> 523<p>If <code>callback</code> is not a function, a <a href="errors.html#class-typeerror"><code>TypeError</code></a> will be thrown.</p> 524<p>This method has a custom variant for promises that is available using 525<a href="#timerspromisessetimmediatevalue-options"><code>timersPromises.setImmediate()</code></a>.</p> 526<h4><code>setInterval(callback[, delay[, ...args]])</code><span><a class="mark" href="#setintervalcallback-delay-args" id="setintervalcallback-delay-args">#</a></span><a aria-hidden="true" class="legacy" id="timers_setinterval_callback_delay_args"></a></h4> 527<div class="api_metadata"> 528<details class="changelog"><summary>History</summary> 529<table> 530<tbody><tr><th>Version</th><th>Changes</th></tr> 531<tr><td>v18.0.0</td> 532<td><p>Passing an invalid callback to the <code>callback</code> argument now throws <code>ERR_INVALID_ARG_TYPE</code> instead of <code>ERR_INVALID_CALLBACK</code>.</p></td></tr> 533<tr><td>v0.0.1</td> 534<td><p><span>Added in: v0.0.1</span></p></td></tr> 535</tbody></table> 536</details> 537</div> 538<ul> 539<li><code>callback</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a> The function to call when the timer elapses.</li> 540<li><code>delay</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> The number of milliseconds to wait before calling the 541<code>callback</code>. <strong>Default:</strong> <code>1</code>.</li> 542<li><code>...args</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> Optional arguments to pass when the <code>callback</code> is called.</li> 543<li>Returns: <a href="timers.html#class-timeout" class="type"><Timeout></a> for use with <a href="#clearintervaltimeout"><code>clearInterval()</code></a></li> 544</ul> 545<p>Schedules repeated execution of <code>callback</code> every <code>delay</code> milliseconds.</p> 546<p>When <code>delay</code> is larger than <code>2147483647</code> or less than <code>1</code>, the <code>delay</code> will be 547set to <code>1</code>. Non-integer delays are truncated to an integer.</p> 548<p>If <code>callback</code> is not a function, a <a href="errors.html#class-typeerror"><code>TypeError</code></a> will be thrown.</p> 549<p>This method has a custom variant for promises that is available using 550<a href="#timerspromisessetintervaldelay-value-options"><code>timersPromises.setInterval()</code></a>.</p> 551<h4><code>setTimeout(callback[, delay[, ...args]])</code><span><a class="mark" href="#settimeoutcallback-delay-args" id="settimeoutcallback-delay-args">#</a></span><a aria-hidden="true" class="legacy" id="timers_settimeout_callback_delay_args"></a></h4> 552<div class="api_metadata"> 553<details class="changelog"><summary>History</summary> 554<table> 555<tbody><tr><th>Version</th><th>Changes</th></tr> 556<tr><td>v18.0.0</td> 557<td><p>Passing an invalid callback to the <code>callback</code> argument now throws <code>ERR_INVALID_ARG_TYPE</code> instead of <code>ERR_INVALID_CALLBACK</code>.</p></td></tr> 558<tr><td>v0.0.1</td> 559<td><p><span>Added in: v0.0.1</span></p></td></tr> 560</tbody></table> 561</details> 562</div> 563<ul> 564<li><code>callback</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type"><Function></a> The function to call when the timer elapses.</li> 565<li><code>delay</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> The number of milliseconds to wait before calling the 566<code>callback</code>. <strong>Default:</strong> <code>1</code>.</li> 567<li><code>...args</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> Optional arguments to pass when the <code>callback</code> is called.</li> 568<li>Returns: <a href="timers.html#class-timeout" class="type"><Timeout></a> for use with <a href="#cleartimeouttimeout"><code>clearTimeout()</code></a></li> 569</ul> 570<p>Schedules execution of a one-time <code>callback</code> after <code>delay</code> milliseconds.</p> 571<p>The <code>callback</code> will likely not be invoked in precisely <code>delay</code> milliseconds. 572Node.js makes no guarantees about the exact timing of when callbacks will fire, 573nor of their ordering. The callback will be called as close as possible to the 574time specified.</p> 575<p>When <code>delay</code> is larger than <code>2147483647</code> or less than <code>1</code>, the <code>delay</code> 576will be set to <code>1</code>. Non-integer delays are truncated to an integer.</p> 577<p>If <code>callback</code> is not a function, a <a href="errors.html#class-typeerror"><code>TypeError</code></a> will be thrown.</p> 578<p>This method has a custom variant for promises that is available using 579<a href="#timerspromisessettimeoutdelay-value-options"><code>timersPromises.setTimeout()</code></a>.</p> 580</section><section><h3>Cancelling timers<span><a class="mark" href="#cancelling-timers" id="cancelling-timers">#</a></span><a aria-hidden="true" class="legacy" id="timers_cancelling_timers"></a></h3> 581<p>The <a href="#setimmediatecallback-args"><code>setImmediate()</code></a>, <a href="#setintervalcallback-delay-args"><code>setInterval()</code></a>, and <a href="#settimeoutcallback-delay-args"><code>setTimeout()</code></a> methods 582each return objects that represent the scheduled timers. These can be used to 583cancel the timer and prevent it from triggering.</p> 584<p>For the promisified variants of <a href="#setimmediatecallback-args"><code>setImmediate()</code></a> and <a href="#settimeoutcallback-delay-args"><code>setTimeout()</code></a>, 585an <a href="globals.html#class-abortcontroller"><code>AbortController</code></a> may be used to cancel the timer. When canceled, the 586returned Promises will be rejected with an <code>'AbortError'</code>.</p> 587<p>For <code>setImmediate()</code>:</p> 588<pre><code class="language-js"><span class="hljs-keyword">const</span> { <span class="hljs-attr">setImmediate</span>: setImmediatePromise } = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:timers/promises'</span>); 589 590<span class="hljs-keyword">const</span> ac = <span class="hljs-keyword">new</span> <span class="hljs-title class_">AbortController</span>(); 591<span class="hljs-keyword">const</span> signal = ac.<span class="hljs-property">signal</span>; 592 593<span class="hljs-title function_">setImmediatePromise</span>(<span class="hljs-string">'foobar'</span>, { signal }) 594 .<span class="hljs-title function_">then</span>(<span class="hljs-variable language_">console</span>.<span class="hljs-property">log</span>) 595 .<span class="hljs-title function_">catch</span>(<span class="hljs-function">(<span class="hljs-params">err</span>) =></span> { 596 <span class="hljs-keyword">if</span> (err.<span class="hljs-property">name</span> === <span class="hljs-string">'AbortError'</span>) 597 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">error</span>(<span class="hljs-string">'The immediate was aborted'</span>); 598 }); 599 600ac.<span class="hljs-title function_">abort</span>();</code> <button class="copy-button">copy</button></pre> 601<p>For <code>setTimeout()</code>:</p> 602<pre><code class="language-js"><span class="hljs-keyword">const</span> { <span class="hljs-attr">setTimeout</span>: setTimeoutPromise } = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:timers/promises'</span>); 603 604<span class="hljs-keyword">const</span> ac = <span class="hljs-keyword">new</span> <span class="hljs-title class_">AbortController</span>(); 605<span class="hljs-keyword">const</span> signal = ac.<span class="hljs-property">signal</span>; 606 607setTimeoutPromise(<span class="hljs-number">1000</span>, <span class="hljs-string">'foobar'</span>, { signal }) 608 .<span class="hljs-title function_">then</span>(<span class="hljs-variable language_">console</span>.<span class="hljs-property">log</span>) 609 .<span class="hljs-title function_">catch</span>(<span class="hljs-function">(<span class="hljs-params">err</span>) =></span> { 610 <span class="hljs-keyword">if</span> (err.<span class="hljs-property">name</span> === <span class="hljs-string">'AbortError'</span>) 611 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">error</span>(<span class="hljs-string">'The timeout was aborted'</span>); 612 }); 613 614ac.<span class="hljs-title function_">abort</span>();</code> <button class="copy-button">copy</button></pre> 615<h4><code>clearImmediate(immediate)</code><span><a class="mark" href="#clearimmediateimmediate" id="clearimmediateimmediate">#</a></span><a aria-hidden="true" class="legacy" id="timers_clearimmediate_immediate"></a></h4> 616<div class="api_metadata"> 617<span>Added in: v0.9.1</span> 618</div> 619<ul> 620<li><code>immediate</code> <a href="timers.html#class-immediate" class="type"><Immediate></a> An <code>Immediate</code> object as returned by 621<a href="#setimmediatecallback-args"><code>setImmediate()</code></a>.</li> 622</ul> 623<p>Cancels an <code>Immediate</code> object created by <a href="#setimmediatecallback-args"><code>setImmediate()</code></a>.</p> 624<h4><code>clearInterval(timeout)</code><span><a class="mark" href="#clearintervaltimeout" id="clearintervaltimeout">#</a></span><a aria-hidden="true" class="legacy" id="timers_clearinterval_timeout"></a></h4> 625<div class="api_metadata"> 626<span>Added in: v0.0.1</span> 627</div> 628<ul> 629<li><code>timeout</code> <a href="timers.html#class-timeout" class="type"><Timeout></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#Number_type" class="type"><number></a> A <code>Timeout</code> object as returned by <a href="#setintervalcallback-delay-args"><code>setInterval()</code></a> 630or the <a href="#timeoutsymboltoprimitive">primitive</a> of the <code>Timeout</code> object as a string or a number.</li> 631</ul> 632<p>Cancels a <code>Timeout</code> object created by <a href="#setintervalcallback-delay-args"><code>setInterval()</code></a>.</p> 633<h4><code>clearTimeout(timeout)</code><span><a class="mark" href="#cleartimeouttimeout" id="cleartimeouttimeout">#</a></span><a aria-hidden="true" class="legacy" id="timers_cleartimeout_timeout"></a></h4> 634<div class="api_metadata"> 635<span>Added in: v0.0.1</span> 636</div> 637<ul> 638<li><code>timeout</code> <a href="timers.html#class-timeout" class="type"><Timeout></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#Number_type" class="type"><number></a> A <code>Timeout</code> object as returned by <a href="#settimeoutcallback-delay-args"><code>setTimeout()</code></a> 639or the <a href="#timeoutsymboltoprimitive">primitive</a> of the <code>Timeout</code> object as a string or a number.</li> 640</ul> 641<p>Cancels a <code>Timeout</code> object created by <a href="#settimeoutcallback-delay-args"><code>setTimeout()</code></a>.</p> 642</section><section><h3>Timers Promises API<span><a class="mark" href="#timers-promises-api" id="timers-promises-api">#</a></span><a aria-hidden="true" class="legacy" id="timers_timers_promises_api"></a></h3> 643<div class="api_metadata"> 644<details class="changelog"><summary>History</summary> 645<table> 646<tbody><tr><th>Version</th><th>Changes</th></tr> 647<tr><td>v16.0.0</td> 648<td><p>Graduated from experimental.</p></td></tr> 649<tr><td>v15.0.0</td> 650<td><p><span>Added in: v15.0.0</span></p></td></tr> 651</tbody></table> 652</details> 653</div> 654<p>The <code>timers/promises</code> API provides an alternative set of timer functions 655that return <code>Promise</code> objects. The API is accessible via 656<code>require('node:timers/promises')</code>.</p> 657 658<pre class="with-13-chars"><input class="js-flavor-selector" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> { 659 <span class="hljs-built_in">setTimeout</span>, 660 setImmediate, 661 <span class="hljs-built_in">setInterval</span>, 662} <span class="hljs-keyword">from</span> <span class="hljs-string">'timers/promises'</span>;</code><code class="language-js cjs"><span class="hljs-keyword">const</span> { 663 <span class="hljs-built_in">setTimeout</span>, 664 setImmediate, 665 <span class="hljs-built_in">setInterval</span>, 666} = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:timers/promises'</span>);</code><button class="copy-button">copy</button></pre> 667<h4><code>timersPromises.setTimeout([delay[, value[, options]]])</code><span><a class="mark" href="#timerspromisessettimeoutdelay-value-options" id="timerspromisessettimeoutdelay-value-options">#</a></span><a aria-hidden="true" class="legacy" id="timers_timerspromises_settimeout_delay_value_options"></a></h4> 668<div class="api_metadata"> 669<span>Added in: v15.0.0</span> 670</div> 671<ul> 672<li><code>delay</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> The number of milliseconds to wait before fulfilling the 673promise. <strong>Default:</strong> <code>1</code>.</li> 674<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> A value with which the promise is fulfilled.</li> 675<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 676<ul> 677<li><code>ref</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> Set to <code>false</code> to indicate that the scheduled <code>Timeout</code> 678should not require the Node.js event loop to remain active. 679<strong>Default:</strong> <code>true</code>.</li> 680<li><code>signal</code> <a href="globals.html#class-abortsignal" class="type"><AbortSignal></a> An optional <code>AbortSignal</code> that can be used to 681cancel the scheduled <code>Timeout</code>.</li> 682</ul> 683</li> 684</ul> 685 686<pre class="with-13-chars"><input class="js-flavor-selector" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> { 687 <span class="hljs-built_in">setTimeout</span>, 688} <span class="hljs-keyword">from</span> <span class="hljs-string">'timers/promises'</span>; 689 690<span class="hljs-keyword">const</span> res = <span class="hljs-keyword">await</span> <span class="hljs-built_in">setTimeout</span>(<span class="hljs-number">100</span>, <span class="hljs-string">'result'</span>); 691 692<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(res); <span class="hljs-comment">// Prints 'result'</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> { 693 <span class="hljs-built_in">setTimeout</span>, 694} = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:timers/promises'</span>); 695 696<span class="hljs-built_in">setTimeout</span>(<span class="hljs-number">100</span>, <span class="hljs-string">'result'</span>).<span class="hljs-title function_">then</span>(<span class="hljs-function">(<span class="hljs-params">res</span>) =></span> { 697 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(res); <span class="hljs-comment">// Prints 'result'</span> 698});</code><button class="copy-button">copy</button></pre> 699<h4><code>timersPromises.setImmediate([value[, options]])</code><span><a class="mark" href="#timerspromisessetimmediatevalue-options" id="timerspromisessetimmediatevalue-options">#</a></span><a aria-hidden="true" class="legacy" id="timers_timerspromises_setimmediate_value_options"></a></h4> 700<div class="api_metadata"> 701<span>Added in: v15.0.0</span> 702</div> 703<ul> 704<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> A value with which the promise is fulfilled.</li> 705<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 706<ul> 707<li><code>ref</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> Set to <code>false</code> to indicate that the scheduled <code>Immediate</code> 708should not require the Node.js event loop to remain active. 709<strong>Default:</strong> <code>true</code>.</li> 710<li><code>signal</code> <a href="globals.html#class-abortsignal" class="type"><AbortSignal></a> An optional <code>AbortSignal</code> that can be used to 711cancel the scheduled <code>Immediate</code>.</li> 712</ul> 713</li> 714</ul> 715 716<pre class="with-15-chars"><input class="js-flavor-selector" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> { 717 setImmediate, 718} <span class="hljs-keyword">from</span> <span class="hljs-string">'timers/promises'</span>; 719 720<span class="hljs-keyword">const</span> res = <span class="hljs-keyword">await</span> <span class="hljs-title function_">setImmediate</span>(<span class="hljs-string">'result'</span>); 721 722<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(res); <span class="hljs-comment">// Prints 'result'</span></code><code class="language-js cjs"><span class="hljs-keyword">const</span> { 723 setImmediate, 724} = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:timers/promises'</span>); 725 726<span class="hljs-title function_">setImmediate</span>(<span class="hljs-string">'result'</span>).<span class="hljs-title function_">then</span>(<span class="hljs-function">(<span class="hljs-params">res</span>) =></span> { 727 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(res); <span class="hljs-comment">// Prints 'result'</span> 728});</code><button class="copy-button">copy</button></pre> 729<h4><code>timersPromises.setInterval([delay[, value[, options]]])</code><span><a class="mark" href="#timerspromisessetintervaldelay-value-options" id="timerspromisessetintervaldelay-value-options">#</a></span><a aria-hidden="true" class="legacy" id="timers_timerspromises_setinterval_delay_value_options"></a></h4> 730<div class="api_metadata"> 731<span>Added in: v15.9.0</span> 732</div> 733<p>Returns an async iterator that generates values in an interval of <code>delay</code> ms. 734If <code>ref</code> is <code>true</code>, you need to call <code>next()</code> of async iterator explicitly 735or implicitly to keep the event loop alive.</p> 736<ul> 737<li><code>delay</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> The number of milliseconds to wait between iterations. 738<strong>Default:</strong> <code>1</code>.</li> 739<li><code>value</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Data_types" class="type"><any></a> A value with which the iterator returns.</li> 740<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 741<ul> 742<li><code>ref</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> Set to <code>false</code> to indicate that the scheduled <code>Timeout</code> 743between iterations should not require the Node.js event loop to 744remain active. 745<strong>Default:</strong> <code>true</code>.</li> 746<li><code>signal</code> <a href="globals.html#class-abortsignal" class="type"><AbortSignal></a> An optional <code>AbortSignal</code> that can be used to 747cancel the scheduled <code>Timeout</code> between operations.</li> 748</ul> 749</li> 750</ul> 751 752<pre class="with-14-chars"><input class="js-flavor-selector" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> { 753 <span class="hljs-built_in">setInterval</span>, 754} <span class="hljs-keyword">from</span> <span class="hljs-string">'timers/promises'</span>; 755 756<span class="hljs-keyword">const</span> interval = <span class="hljs-number">100</span>; 757<span class="hljs-keyword">for</span> <span class="hljs-keyword">await</span> (<span class="hljs-keyword">const</span> startTime <span class="hljs-keyword">of</span> <span class="hljs-built_in">setInterval</span>(interval, <span class="hljs-title class_">Date</span>.<span class="hljs-title function_">now</span>())) { 758 <span class="hljs-keyword">const</span> now = <span class="hljs-title class_">Date</span>.<span class="hljs-title function_">now</span>(); 759 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(now); 760 <span class="hljs-keyword">if</span> ((now - startTime) > <span class="hljs-number">1000</span>) 761 <span class="hljs-keyword">break</span>; 762} 763<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Date</span>.<span class="hljs-title function_">now</span>());</code><code class="language-js cjs"><span class="hljs-keyword">const</span> { 764 <span class="hljs-built_in">setInterval</span>, 765} = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:timers/promises'</span>); 766<span class="hljs-keyword">const</span> interval = <span class="hljs-number">100</span>; 767 768(<span class="hljs-keyword">async</span> <span class="hljs-keyword">function</span>(<span class="hljs-params"></span>) { 769 <span class="hljs-keyword">for</span> <span class="hljs-keyword">await</span> (<span class="hljs-keyword">const</span> startTime <span class="hljs-keyword">of</span> <span class="hljs-built_in">setInterval</span>(interval, <span class="hljs-title class_">Date</span>.<span class="hljs-title function_">now</span>())) { 770 <span class="hljs-keyword">const</span> now = <span class="hljs-title class_">Date</span>.<span class="hljs-title function_">now</span>(); 771 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(now); 772 <span class="hljs-keyword">if</span> ((now - startTime) > <span class="hljs-number">1000</span>) 773 <span class="hljs-keyword">break</span>; 774 } 775 <span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title class_">Date</span>.<span class="hljs-title function_">now</span>()); 776})();</code><button class="copy-button">copy</button></pre> 777<h4><code>timersPromises.scheduler.wait(delay[, options])</code><span><a class="mark" href="#timerspromisesschedulerwaitdelay-options" id="timerspromisesschedulerwaitdelay-options">#</a></span><a aria-hidden="true" class="legacy" id="timers_timerspromises_scheduler_wait_delay_options"></a></h4> 778<div class="api_metadata"> 779<span>Added in: v17.3.0, v16.14.0</span> 780</div> 781<p></p><div class="api_stability api_stability_1"><a href="documentation.html#stability-index">Stability: 1</a> - Experimental</div><p></p> 782<ul> 783<li><code>delay</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> The number of milliseconds to wait before resolving the 784promise.</li> 785<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> 786<ul> 787<li><code>signal</code> <a href="globals.html#class-abortsignal" class="type"><AbortSignal></a> An optional <code>AbortSignal</code> that can be used to 788cancel waiting.</li> 789</ul> 790</li> 791<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type"><Promise></a></li> 792</ul> 793<p>An experimental API defined by the <a href="https://github.com/WICG/scheduling-apis">Scheduling APIs</a> draft specification 794being developed as a standard Web Platform API.</p> 795<p>Calling <code>timersPromises.scheduler.wait(delay, options)</code> is roughly equivalent 796to calling <code>timersPromises.setTimeout(delay, undefined, options)</code> except that 797the <code>ref</code> option is not supported.</p> 798<pre><code class="language-js mjs"><span class="hljs-keyword">import</span> { scheduler } <span class="hljs-keyword">from</span> <span class="hljs-string">'node:timers/promises'</span>; 799 800<span class="hljs-keyword">await</span> scheduler.<span class="hljs-title function_">wait</span>(<span class="hljs-number">1000</span>); <span class="hljs-comment">// Wait one second before continuing</span></code> <button class="copy-button">copy</button></pre> 801<h4><code>timersPromises.scheduler.yield()</code><span><a class="mark" href="#timerspromisesscheduleryield" id="timerspromisesscheduleryield">#</a></span><a aria-hidden="true" class="legacy" id="timers_timerspromises_scheduler_yield"></a></h4> 802<div class="api_metadata"> 803<span>Added in: v17.3.0, v16.14.0</span> 804</div> 805<p></p><div class="api_stability api_stability_1"><a href="documentation.html#stability-index">Stability: 1</a> - Experimental</div><p></p> 806<ul> 807<li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise" class="type"><Promise></a></li> 808</ul> 809<p>An experimental API defined by the <a href="https://github.com/WICG/scheduling-apis">Scheduling APIs</a> draft specification 810being developed as a standard Web Platform API.</p> 811<p>Calling <code>timersPromises.scheduler.yield()</code> is equivalent to calling 812<code>timersPromises.setImmediate()</code> with no arguments.</p></section> 813 <!-- API END --> 814 </div> 815 </div> 816 </div> 817</body> 818</html> 819