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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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