tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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delay-test.html (2715B)

      1 <!DOCTYPE html>
      2 <meta name="viewport" content="width=device-width,initial-scale=1">
      3 <script src="/resources/testharness.js"></script>
      4 <script src="/resources/testharnessreport.js"></script>
      5 <script src="../resources/intersection-observer-test-utils.js"></script>
      6 
      7 <style>
      8 body, html {
      9  margin: 0;
     10 }
     11 pre, #log {
     12  position: absolute;
     13  top: 0;
     14  left: 200px;
     15 }
     16 #target {
     17  width: 100px;
     18  height: 100px;
     19  background-color: green;
     20 }
     21 #occluder {
     22  width: 100px;
     23  height: 100px;
     24  background-color: blue;
     25 }
     26 </style>
     27 
     28 <div id="target"></div>
     29 <div id="occluder"></div>
     30 
     31 <script>
     32 async_test(t => {
     33  let entries = [];
     34  let delay = 100;
     35  let target = document.getElementById("target");
     36  let occluder = document.getElementById("occluder");
     37 
     38  assert_true(!!target, "target exists");
     39  assert_true(!!occluder, "occluder exists");
     40  let observer = new IntersectionObserver(function(changes) {
     41    entries = entries.concat(changes)
     42  }, {trackVisibility: true, delay: delay});
     43  observer.observe(target);
     44  entries = entries.concat(observer.takeRecords());
     45  assert_equals(entries.length, 0, "No initial notifications.");
     46  // The first notification should be sent without delay.
     47  waitForNotification(t, t.step_func(step0));
     48 
     49  function waitForDelay(timerExpiredBeforeLastFrame, nextStep) {
     50    requestAnimationFrame(t.step_func(() => {
     51      if (timerExpiredBeforeLastFrame) {
     52        // New notifications should have been generated during the previous
     53        // frame and delivered by now.
     54        assert_equals(entries.length, 2);
     55        assert_greater_than(entries[1].time - entries[0].time, delay);
     56        assert_false(entries[1].isVisible);
     57        nextStep();
     58      } else {
     59        // Observer may not have updated yet. Wait for next frame.
     60        let timerExpired = performance.now() - entries[0].time >= delay;
     61        waitForDelay(timerExpired, nextStep);
     62      }
     63    }));
     64  }
     65 
     66  function step0() {
     67    assert_equals(entries.length, 1);
     68    assert_true(entries[0].isVisible);
     69    // This should trigger a notification on the next run.
     70    occluder.style.marginTop = "-10px";
     71    // Enter a rAF loop until the delay timer expires.
     72    waitForDelay(false, step1);
     73  }
     74 
     75  function step1() {
     76    occluder.style.marginTop = "10px";
     77    // This style invalidation should cause a frame to run before the observer
     78    // can generate a notification (due to delay parameter). Make sure the
     79    // notification will still be generated even if we don't force more frames
     80    // with a rAF loop.
     81    t.step_timeout(() => {
     82      assert_equals(entries.length, 3);
     83      assert_true(entries[0].isVisible);
     84      t.done();
     85    }, 2 * delay);
     86  }
     87 
     88 }, "'delay' parameter throttles frequency of notifications.");
     89 </script>