task_microtask_ordering.html | Explore in Territory

<!DOCTYPE html>
<title>Task and Microtask Ordering </title>
<link rel=author title="Joshua Bell" href="mailto:[email protected]">
<link rel=help href="https://html.spec.whatwg.org/multipage/#event-loops">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/common.js"></script>

<div class="outer">
  <div class="inner"></div>
</div>

<script>

// Based on: https://jakearchibald.com/2015/tasks-microtasks-queues-and-schedules/

log_test(function(t, log) {
    log('script start');

    setTimeout(function() {
        log('setTimeout');
    }, 0);

    Promise.resolve().then(function() {
        log('promise1');
    }).then(function() {
        log('promise2');
    });

    log('script end');
}, [
    'script start',
    'script end',
    'promise1',
    'promise2',
    'setTimeout'
], 'Basic task and microtask ordering');

log_test(function(t, log) {
    // Let's get hold of those elements
    var outer = document.querySelector('.outer');
    var inner = document.querySelector('.inner');

    // Let's listen for attribute changes on the
    // outer element
    new MutationObserver(function() {
        log('mutate');
    }).observe(outer, {
        attributes: true
    });

    // Here's a click listener...
    function onClick() {
        log('click');

        setTimeout(function() {
            log('timeout');
        }, 0);

        Promise.resolve().then(function() {
            log('promise');
        });

        outer.setAttribute('data-random', Math.random());
    }

    // ...which we'll attach to both elements
    inner.addEventListener('click', onClick);
    outer.addEventListener('click', onClick);

    // Note that this will behave differently than a real click,
    // since the dispatch is synchronous and microtasks will not
    // run between event bubbling steps.
    inner.click();
}, [
    'click',
    'click',
    'promise',
    'mutate',
    'promise',
    'timeout',
    'timeout'
], 'Level 1 bossfight (synthetic click)');

</script>
chromium/third_party/blink/web_tests/external/wpt/html/webappapis/scripting/event-loops/task_microtask_ordering.html
