How to use mutationObserverMicrotask method in wpt
Best JavaScript code snippet using wpt
promise-rejection-events.js
Source:promise-rejection-events.js 
...80 onUnhandledSucceed(t, e2, function() { return promise2; });81 var promise = new Promise(function(_, reject) {82 setTimeout(function() {83 reject(e);84 mutationObserverMicrotask(function() {85 var unreached = t.unreached_func('promise should not be fulfilled');86 promise2 = promise.then(unreached, function(reason) {87 t.step(function() {88 assert_equals(reason, e);89 });90 throw e2;91 });92 });93 }, 1);94 });95}, 'unhandledrejection: from a throw in a rejection handler attached one microtask after a setTimeout-delayed rejection');96async_test(function(t) {97 var e = new Error();98 var p;99 onUnhandledSucceed(t, e, function() { return p; });100 p = Promise.resolve().then(function() {101 return Promise.reject(e);102 });103}, 'unhandledrejection: from returning a Promise.reject-created rejection in a fulfillment handler');104async_test(function(t) {105 var e = new Error();106 var p;107 onUnhandledSucceed(t, e, function() { return p; });108 p = Promise.resolve().then(function() {109 throw e;110 });111}, 'unhandledrejection: from a throw in a fulfillment handler');112async_test(function(t) {113 var e = new Error();114 var p;115 onUnhandledSucceed(t, e, function() { return p; });116 p = Promise.resolve().then(function() {117 return new Promise(function(_, reject) {118 setTimeout(function() {119 reject(e);120 }, 1);121 });122 });123}, 'unhandledrejection: from returning a setTimeout-delayed rejection in a fulfillment handler');124async_test(function(t) {125 var e = new Error();126 var p;127 onUnhandledSucceed(t, e, function() { return p; });128 p = Promise.all([Promise.reject(e)]);129}, 'unhandledrejection: from Promise.reject, indirected through Promise.all');130//131// Negative unhandledrejection/rejectionhandled tests with immediate attachment132//133async_test(function(t) {134 var e = new Error();135 var p;136 onUnhandledFail(t, function() { return p; });137 var unreached = t.unreached_func('promise should not be fulfilled');138 p = Promise.reject(e).then(unreached, function() {});139}, 'no unhandledrejection/rejectionhandled: rejection handler attached synchronously to a promise from Promise.reject');140async_test(function(t) {141 var e = new Error();142 var p;143 onUnhandledFail(t, function() { return p; });144 var unreached = t.unreached_func('promise should not be fulfilled');145 p = Promise.all([Promise.reject(e)]).then(unreached, function() {});146}, 'no unhandledrejection/rejectionhandled: rejection handler attached synchronously to a promise from ' +147 'Promise.reject, indirecting through Promise.all');148async_test(function(t) {149 var e = new Error();150 var p;151 onUnhandledFail(t, function() { return p; });152 var unreached = t.unreached_func('promise should not be fulfilled');153 p = new Promise(function(_, reject) {154 reject(e);155 }).then(unreached, function() {});156}, 'no unhandledrejection/rejectionhandled: rejection handler attached synchronously to a synchronously-rejected ' +157 'promise created with new Promise');158async_test(function(t) {159 var e = new Error();160 var p;161 onUnhandledFail(t, function() { return p; });162 var unreached = t.unreached_func('promise should not be fulfilled');163 p = Promise.resolve().then(function() {164 throw e;165 }).then(unreached, function(reason) {166 t.step(function() {167 assert_equals(reason, e);168 });169 });170}, 'no unhandledrejection/rejectionhandled: rejection handler attached synchronously to a promise created from ' +171 'throwing in a fulfillment handler');172async_test(function(t) {173 var e = new Error();174 var p;175 onUnhandledFail(t, function() { return p; });176 var unreached = t.unreached_func('promise should not be fulfilled');177 p = Promise.resolve().then(function() {178 return Promise.reject(e);179 }).then(unreached, function(reason) {180 t.step(function() {181 assert_equals(reason, e);182 });183 });184}, 'no unhandledrejection/rejectionhandled: rejection handler attached synchronously to a promise created from ' +185 'returning a Promise.reject-created promise in a fulfillment handler');186async_test(function(t) {187 var e = new Error();188 var p;189 onUnhandledFail(t, function() { return p; });190 var unreached = t.unreached_func('promise should not be fulfilled');191 p = Promise.resolve().then(function() {192 return new Promise(function(_, reject) {193 setTimeout(function() {194 reject(e);195 }, 1);196 });197 }).then(unreached, function(reason) {198 t.step(function() {199 assert_equals(reason, e);200 });201 });202}, 'no unhandledrejection/rejectionhandled: rejection handler attached synchronously to a promise created from ' +203 'returning a setTimeout-delayed rejection in a fulfillment handler');204async_test(function(t) {205 var e = new Error();206 var p;207 onUnhandledFail(t, function() { return p; });208 postMessageTask(function() {209 p = Promise.resolve().then(function() {210 return Promise.reject(e);211 })212 .catch(function() {});213 });214}, 'no unhandledrejection/rejectionhandled: all inside a queued task, a rejection handler attached synchronously to ' +215 'a promise created from returning a Promise.reject-created promise in a fulfillment handler');216//217// Negative unhandledrejection/rejectionhandled tests with microtask-delayed attachment218//219async_test(function(t) {220 var e = new Error();221 var p;222 onUnhandledFail(t, function() { return p; });223 p = Promise.reject(e);224 mutationObserverMicrotask(function() {225 var unreached = t.unreached_func('promise should not be fulfilled');226 p.then(unreached, function() {});227 });228}, 'delayed handling: a microtask delay before attaching a handler prevents both events (Promise.reject-created ' +229 'promise)');230async_test(function(t) {231 var e = new Error();232 var p;233 onUnhandledFail(t, function() { return p; });234 p = new Promise(function(_, reject) {235 reject(e);236 });237 mutationObserverMicrotask(function() {238 var unreached = t.unreached_func('promise should not be fulfilled');239 p.then(unreached, function() {});240 });241}, 'delayed handling: a microtask delay before attaching a handler prevents both events (immediately-rejected new ' +242 'Promise-created promise)');243async_test(function(t) {244 var e = new Error();245 var p1;246 var p2;247 onUnhandledFail(t, function() { return p1; });248 onUnhandledFail(t, function() { return p2; });249 p1 = new Promise(function(_, reject) {250 mutationObserverMicrotask(function() {251 reject(e);252 });253 });254 p2 = Promise.all([p1]);255 mutationObserverMicrotask(function() {256 var unreached = t.unreached_func('promise should not be fulfilled');257 p2.then(unreached, function() {});258 });259}, 'delayed handling: a microtask delay before attaching the handler, and before rejecting the promise, indirected ' +260 'through Promise.all');261//262// Negative unhandledrejection/rejectionhandled tests with nested-microtask-delayed attachment263//264async_test(function(t) {265 var e = new Error();266 var p;267 onUnhandledFail(t, function() { return p; });268 p = Promise.reject(e);269 mutationObserverMicrotask(function() {270 Promise.resolve().then(function() {271 mutationObserverMicrotask(function() {272 Promise.resolve().then(function() {273 p.catch(function() {});274 });275 });276 });277 });278}, 'microtask nesting: attaching a handler inside a combination of mutationObserverMicrotask + promise microtasks');279async_test(function(t) {280 var e = new Error();281 var p;282 onUnhandledFail(t, function() { return p; });283 postMessageTask(function() {284 p = Promise.reject(e);285 mutationObserverMicrotask(function() {286 Promise.resolve().then(function() {287 mutationObserverMicrotask(function() {288 Promise.resolve().then(function() {289 p.catch(function() {});290 });291 });292 });293 });294 });295}, 'microtask nesting: attaching a handler inside a combination of mutationObserverMicrotask + promise microtasks, ' +296 'all inside a postMessageTask');297async_test(function(t) {298 var e = new Error();299 var p;300 onUnhandledFail(t, function() { return p; });301 setTimeout(function() {302 p = Promise.reject(e);303 mutationObserverMicrotask(function() {304 Promise.resolve().then(function() {305 mutationObserverMicrotask(function() {306 Promise.resolve().then(function() {307 p.catch(function() {});308 });309 });310 });311 });312 }, 0);313}, 'microtask nesting: attaching a handler inside a combination of mutationObserverMicrotask + promise microtasks, ' +314 'all inside a setTimeout');315async_test(function(t) {316 var e = new Error();317 var p;318 onUnhandledFail(t, function() { return p; });319 p = Promise.reject(e);320 Promise.resolve().then(function() {321 mutationObserverMicrotask(function() {322 Promise.resolve().then(function() {323 mutationObserverMicrotask(function() {324 p.catch(function() {});325 });326 });327 });328 });329}, 'microtask nesting: attaching a handler inside a combination of promise microtasks + mutationObserverMicrotask');330async_test(function(t) {331 var e = new Error();332 var p;333 onUnhandledFail(t, function() { return p; });334 postMessageTask(function() {335 p = Promise.reject(e);336 Promise.resolve().then(function() {337 mutationObserverMicrotask(function() {338 Promise.resolve().then(function() {339 mutationObserverMicrotask(function() {340 p.catch(function() {});341 });342 });343 });344 });345 });346}, 'microtask nesting: attaching a handler inside a combination of promise microtasks + mutationObserverMicrotask, ' +347 'all inside a postMessageTask');348async_test(function(t) {349 var e = new Error();350 var p;351 onUnhandledFail(t, function() { return p; });352 setTimeout(function() {353 p = Promise.reject(e);354 Promise.resolve().then(function() {355 mutationObserverMicrotask(function() {356 Promise.resolve().then(function() {357 mutationObserverMicrotask(function() {358 p.catch(function() {});359 });360 });361 });362 });363 }, 0);364}, 'microtask nesting: attaching a handler inside a combination of promise microtasks + mutationObserverMicrotask, ' +365 'all inside a setTimeout');366// For workers, postMessageTask() involves posting tasks to other threads, so367// the following tests don't work there.368if ('document' in self) {369 //370 // Negative unhandledrejection/rejectionhandled tests with task-delayed attachment371 //372 async_test(function(t) {373 var e = new Error();374 var p;375 onUnhandledFail(t, function() { return p; });376 var _reject;377 p = new Promise(function(_, reject) {378 _reject = reject;379 });380 _reject(e);381 postMessageTask(function() {382 var unreached = t.unreached_func('promise should not be fulfilled');383 p.then(unreached, function() {});384 });385 }, 'delayed handling: a task delay before attaching a handler prevents unhandledrejection');386 async_test(function(t) {387 var e = new Error();388 var p;389 onUnhandledFail(t, function() { return p; });390 p = Promise.reject(e);391 postMessageTask(function() {392 Promise.resolve().then(function() {393 p.catch(function() {});394 });395 });396 }, 'delayed handling: postMessageTask after promise creation/rejection, plus promise microtasks, is not too late to ' +397 'attach a rejection handler');398 async_test(function(t) {399 var e = new Error();400 var p;401 onUnhandledFail(t, function() { return p; });402 postMessageTask(function() {403 Promise.resolve().then(function() {404 Promise.resolve().then(function() {405 Promise.resolve().then(function() {406 Promise.resolve().then(function() {407 p.catch(function() {});408 });409 });410 });411 });412 });413 p = Promise.reject(e);414 }, 'delayed handling: postMessageTask before promise creation/rejection, plus many promise microtasks, is not too ' +415 'late to attach a rejection handler');416 async_test(function(t) {417 var e = new Error();418 var p;419 onUnhandledFail(t, function() { return p; });420 p = Promise.reject(e);421 postMessageTask(function() {422 Promise.resolve().then(function() {423 Promise.resolve().then(function() {424 Promise.resolve().then(function() {425 Promise.resolve().then(function() {426 p.catch(function() {});427 });428 });429 });430 });431 });432 }, 'delayed handling: postMessageTask after promise creation/rejection, plus many promise microtasks, is not too ' +433 'late to attach a rejection handler');434}435//436// Positive unhandledrejection/rejectionhandled tests with delayed attachment437//438async_test(function(t) {439 var e = new Error();440 var p;441 onUnhandledSucceed(t, e, function() { return p; });442 var _reject;443 p = new Promise(function(_, reject) {444 _reject = reject;445 });446 _reject(e);447 postMessageTask(function() {448 postMessageTask(function() {449 var unreached = t.unreached_func('promise should not be fulfilled');450 p.then(unreached, function() {});451 });452 });453}, 'delayed handling: a nested-task delay before attaching a handler causes unhandledrejection');454async_test(function(t) {455 var e = new Error();456 var p;457 onUnhandledSucceed(t, e, function() { return p; });458 p = Promise.reject(e);459 postMessageTask(function() {460 postMessageTask(function() {461 Promise.resolve().then(function() {462 p.catch(function() {});463 });464 });465 });466}, 'delayed handling: a nested-postMessageTask after promise creation/rejection, plus promise microtasks, is too ' +467 'late to attach a rejection handler');468async_test(function(t) {469 var e = new Error();470 var p;471 onUnhandledSucceed(t, e, function() { return p; });472 postMessageTask(function() {473 postMessageTask(function() {474 Promise.resolve().then(function() {475 Promise.resolve().then(function() {476 Promise.resolve().then(function() {477 Promise.resolve().then(function() {478 p.catch(function() {});479 });480 });481 });482 });483 });484 });485 p = Promise.reject(e);486}, 'delayed handling: a nested-postMessageTask before promise creation/rejection, plus many promise microtasks, is ' +487 'too late to attach a rejection handler');488async_test(function(t) {489 var e = new Error();490 var p;491 onUnhandledSucceed(t, e, function() { return p; });492 p = Promise.reject(e);493 postMessageTask(function() {494 postMessageTask(function() {495 Promise.resolve().then(function() {496 Promise.resolve().then(function() {497 Promise.resolve().then(function() {498 Promise.resolve().then(function() {499 p.catch(function() {});500 });501 });502 });503 });504 });505 });506}, 'delayed handling: a nested-postMessageTask after promise creation/rejection, plus many promise microtasks, is ' +507 'too late to attach a rejection handler');508async_test(function(t) {509 var unhandledPromises = [];510 var unhandledReasons = [];511 var e = new Error();512 var p;513 var unhandled = function(ev) {514 if (ev.promise === p) {515 t.step(function() {516 unhandledPromises.push(ev.promise);517 unhandledReasons.push(ev.reason);518 });519 }520 };521 var handled = function(ev) {522 if (ev.promise === p) {523 t.step(function() {524 assert_array_equals(unhandledPromises, [p]);525 assert_array_equals(unhandledReasons, [e]);526 assert_equals(ev.promise, p);527 assert_equals(ev.reason, e);528 });529 }530 };531 addEventListener('unhandledrejection', unhandled);532 addEventListener('rejectionhandled', handled);533 ensureCleanup(t, unhandled, handled);534 p = new Promise(function() {535 throw e;536 });537 setTimeout(function() {538 var unreached = t.unreached_func('promise should not be fulfilled');539 p.then(unreached, function(reason) {540 assert_equals(reason, e);541 setTimeout(function() { t.done(); }, 10);542 });543 }, 10);544}, 'delayed handling: delaying handling by setTimeout(,10) will cause both events to fire');545//546// Miscellaneous tests about integration with the rest of the platform547//548async_test(function(t) {549 var e = new Error();550 var l = function(ev) {551 var order = [];552 mutationObserverMicrotask(function() {553 order.push(1);554 });555 setTimeout(function() {556 order.push(2);557 t.step(function() {558 assert_array_equals(order, [1, 2]);559 });560 t.done();561 }, 1);562 };563 addEventListener('unhandledrejection', l);564 ensureCleanup(t, l);565 Promise.reject(e);566}, 'mutationObserverMicrotask vs. postMessageTask ordering is not disturbed inside unhandledrejection events');567// For workers, postMessageTask() involves posting tasks to other threads, so568// the following tests don't work there.569if ('document' in self) {570 // For the next two see https://github.com/domenic/unhandled-rejections-browser-spec/issues/2#issuecomment-121121695571 // and the following comments.572 async_test(function(t) {573 var sequenceOfEvents = [];574 addEventListener('unhandledrejection', l);575 ensureCleanup(t, l);576 var p1 = Promise.reject();577 var p2;578 postMessageTask(function() {579 p2 = Promise.reject();580 postMessageTask(function() {581 sequenceOfEvents.push('postMessageTask');582 checkSequence();583 });584 });585 function l(ev) {586 if (ev.promise === p1 || ev.promise === p2) {587 sequenceOfEvents.push(ev.promise);588 checkSequence();589 }590 }591 function checkSequence() {592 if (sequenceOfEvents.length === 3) {593 t.step(function() {594 assert_array_equals(sequenceOfEvents, [p1, 'postMessageTask', p2]);595 });596 t.done();597 }598 }599 }, 'postMessageTask ordering vs. the task queued for unhandled rejection notification (1)');600 async_test(function(t) {601 var sequenceOfEvents = [];602 addEventListener('unhandledrejection', l);603 ensureCleanup(t, l);604 var p2;605 postMessageTask(function() {606 p2 = Promise.reject();607 postMessageTask(function() {608 sequenceOfEvents.push('postMessageTask');609 checkSequence();610 });611 });612 function l(ev) {613 if (ev.promise == p2) {614 sequenceOfEvents.push(ev.promise);615 checkSequence();616 }617 }618 function checkSequence() {619 if (sequenceOfEvents.length === 2) {620 t.step(function() {621 assert_array_equals(sequenceOfEvents, ['postMessageTask', p2]);622 });623 t.done();624 }625 }626 }, 'postMessageTask ordering vs. the task queued for unhandled rejection notification (2)');627 async_test(function(t) {628 var sequenceOfEvents = [];629 addEventListener('unhandledrejection', unhandled);630 addEventListener('rejectionhandled', handled);631 ensureCleanup(t, unhandled, handled);632 var p = Promise.reject();633 setTimeout(function() {634 postMessageTask(function() {635 sequenceOfEvents.push('task before catch');636 checkSequence();637 });638 p.catch(function() {639 sequenceOfEvents.push('catch');640 checkSequence();641 });642 postMessageTask(function() {643 sequenceOfEvents.push('task after catch');644 checkSequence();645 });646 sequenceOfEvents.push('after catch');647 checkSequence();648 }, 10);649 function unhandled(ev) {650 if (ev.promise === p) {651 sequenceOfEvents.push('unhandled');652 checkSequence();653 }654 }655 function handled(ev) {656 if (ev.promise === p) {657 sequenceOfEvents.push('handled');658 checkSequence();659 }660 }661 function checkSequence() {662 if (sequenceOfEvents.length === 6) {663 t.step(function() {664 assert_array_equals(sequenceOfEvents,665 ['unhandled', 'after catch', 'catch', 'task before catch', 'handled', 'task after catch']);666 });667 t.done();668 }669 }670 }, 'rejectionhandled is dispatched from a queued task, and not immediately');671}672//673// HELPERS674//675var globalPostMessageCounter = 0;676function postMessageTask(f) {677 if ('document' in self) {678 var message = 'abusingpostmessageforfunandprofit' + globalPostMessageCounter;679 globalPostMessageCounter++;680 var l = function(ev) {681 if (ev.data === message) {682 removeEventListener('message', l);683 f();684 }685 };686 addEventListener('message', l);687 postMessage(message, '*');688 } else {689 var channel = new MessageChannel();690 channel.port1.onmessage = function() { channel.port1.close(); f(); };691 channel.port2.postMessage('abusingpostmessageforfunandprofit');692 channel.port2.close();693 }694}695function mutationObserverMicrotask(f) {696 if ('document' in self) {697 var observer = new MutationObserver(function() { f(); });698 var node = document.createTextNode('');699 observer.observe(node, { characterData: true });700 node.data = 'foo';701 } else {702 // We don't have mutation observers on workers, so just post a promise-based703 // microtask.704 Promise.resolve().then(function() { f(); });705 }706}707function onUnhandledSucceed(t, expectedReason, expectedPromiseGetter) {708 var l = function(ev) {709 if (ev.promise === expectedPromiseGetter()) {...
Using AI Code Generation
1var MutationObserver = window.MutationObserver || window.WebKitMutationObserver;2var observer = new MutationObserver(function(mutations) {3 mutations.forEach(function(mutation) {4 console.log(mutation.type);5 });6});7var target = document.querySelector('#someElement');8var config = { attributes: true, childList: true, characterData: true };9observer.observe(target, config);10target.setAttribute('foo', 'bar');
Using AI Code Generation
1test(function() {2 var div = document.createElement('div');3 var observer = new MutationObserver(function() {});4 observer.observe(div, {attributes: true});5 div.setAttribute('foo', 'bar');6 assert_true(mutationObserverMicrotask());7}, 'mutationObserverMicrotask returns true when a microtask is pending');8test(function() {9 var div = document.createElement('div');10 var observer = new MutationObserver(function() {});11 observer.observe(div, {attributes: true});12 div.setAttribute('foo', 'bar');13 assert_false(mutationObserverMicrotask());14}, 'mutationObserverMicrotask returns false when no microtask is pending');15test(function() {16 var div = document.createElement('div');17 var observer = new MutationObserver(function() {});18 observer.observe(div, {attributes: true});19 div.setAttribute('foo', 'bar');20 assert_true(mutationObserverMicrotask());21}, 'mutationObserverMicrotask returns true when a microtask is pending');22test(function() {23 var div = document.createElement('div');24 var observer = new MutationObserver(function() {});25 observer.observe(div, {attributes: true});26 div.setAttribute('foo', 'bar');27 assert_false(mutationObserverMicrotask());28}, 'mutationObserverMicrotask returns false when no microtask is pending');29test(function() {30 var div = document.createElement('div');31 var observer = new MutationObserver(function() {});32 observer.observe(div, {attributes: true});33 div.setAttribute('foo', 'bar');34 assert_true(mutationObserverMicrotask());35}, 'mutationObserverMicrotask returns true when a microtask is pending');36test(function() {37 var div = document.createElement('div');38 var observer = new MutationObserver(function() {});39 observer.observe(div, {attributes: true});40 div.setAttribute('foo', 'bar');41 assert_false(mutationObserverMicrotask());42}, 'mutationObserverMicrotask returns false when no microtask is pending');43test(function() {44 var div = document.createElement('div');45 var observer = new MutationObserver(function() {});
Using AI Code Generation
1import { defineCE, fixture } from '@open-wc/testing-helpers';2import { html, LitElement } from 'lit';3import { expect, fixtureSync } from '@open-wc/testing';4import { MyElement } from '../src/MyElement.js';5describe('MyElement', () => {6 let el;7 beforeEach(async () => {8 const tag = defineCE(9 class extends LitElement {10 render() {11 return html`<my-element></my-element>`;12 }13 },14 );15 el = await fixture(`<${tag}></${tag}>`);16 });17 it('passes the a11y audit', async () => {18 await expect(el).shadowDom.to.be.accessible();19 });20});
Using AI Code Generation
1function mutationObserverMicrotask(func) {2 var observer = new MutationObserver(function() {3 observer.disconnect();4 func();5 });6 observer.observe(document.documentElement, { attributes: true });7 document.documentElement.setAttribute('data-mutation', '1');8}9test(function() {10 var iframe = document.createElement('iframe');11 document.body.appendChild(iframe);12 iframe.contentDocument.write('Hello world');13 mutationObserverMicrotask(function() {14 assert_equals(iframe.contentDocument.body.textContent, 'Hello world');15 iframe.remove();16 this.done();17 }.bind(this));18}, 'Iframe should have loaded');
Using AI Code Generation
1import {mutationObserverMicrotask} from "wpt-runner";2describe("MutationObserver", function() {3 it("should work", function() {4 mutationObserverMicrotask(function() {5 });6 });7});8This is a polyfill for MutationObserver. It is based on [MutationObserver.js](
Using AI Code Generation
1const { mutationObserverMicrotask } = require('wpt-runner');2const { document } = require('global/window');3describe('MutationObserver', () => {4 it('should observe changes to the DOM', async () => {5 const div = document.createElement('div');6 document.body.appendChild(div);7 const observer = new MutationObserver(mutationObserverMicrotask);8 const promise = new Promise((resolve) => {9 observer.observe(div, {10 });11 observer.onMutation = (mutations) => {12 resolve(mutations);13 };14 });15 const child = document.createElement('span');16 div.appendChild(child);17 const mutations = await promise;18 expect(mutations.length).to.equal(1);19 expect(mutations[0].addedNodes.length).to.equal(1);20 expect(mutations[0].addedNodes[0]).to.equal(child);21 });22});23we recommend using [mutationobserver-shim](
Using AI Code Generation
1import { mutationObserverMicrotask } from 'wpt-runner';2export default async function() {3 const el = document.createElement('div');4 document.body.appendChild(el);5 const mo = new MutationObserver(() => {});6 mo.observe(el, { attributes: true });7 el.setAttribute('foo', 'bar');8 await mutationObserverMicrotask();9}
Using AI Code Generation
1import { mutationObserverMicrotask } from "wpt-runner";2test("MutationObserver", async () => {3 const element = document.createElement("div");4 document.body.appendChild(element);5 const observer = new MutationObserver(mutationList => {6 console.log("MutationObserver triggered");7 });8 const config = { attributes: true, childList: true, subtree: true };9 observer.observe(element, config);10 element.setAttribute("test", "test");11 await mutationObserverMicrotask();12});13observe()14disconnect()15takeRecords()16The observe() method is used to start observing the DOM for changes. It takes two parameters: target and options. The target parameter is the DOM element to observe. The options parameter is an object with the following properties:
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