multiple-targets.html

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This WPT test may be referenced by the following Test IDs:
- /intersection-observer/multiple-targets.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<meta name="viewport" content="width=device-width,initial-scale=1">

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script src="./resources/intersection-observer-test-utils.js"></script>

<style>

pre, #log {

  position: absolute;

  top: 0;

  left: 200px;

.spacer {

  height: calc(100vh + 100px);

.target {

  width: 100px;

  height: 100px;

  margin: 10px;

  background-color: green;

</style>

<div class="spacer"></div>

<div id="target1" class="target"></div>

<div id="target2" class="target"></div>

<div id="target3" class="target"></div>

<script>

var entries = [];

var target1, target2, target3;

runTestCycle(function() {

  target1 = document.getElementById("target1");

  assert_true(!!target1, "target1 exists.");

  target2 = document.getElementById("target2");

  assert_true(!!target2, "target2 exists.");

  target3 = document.getElementById("target3");

  assert_true(!!target3, "target3 exists.");

  var observer = new IntersectionObserver(function(changes) {

    entries = entries.concat(changes)

});

  observer.observe(target1);

  observer.observe(target2);

  observer.observe(target3);

  entries = entries.concat(observer.takeRecords());

  assert_equals(entries.length, 0, "No initial notifications.");

  runTestCycle(step0, "First rAF.");

}, "One observer with multiple targets.");

function step0() {

  document.scrollingElement.scrollTop = 150;

  runTestCycle(step1, "document.scrollingElement.scrollTop = 150");

  assert_equals(entries.length, 3, "Three initial notifications.");

  assert_equals(entries[0].target, target1, "entries[0].target === target1");

  assert_equals(entries[1].target, target2, "entries[1].target === target2");

  assert_equals(entries[2].target, target3, "entries[2].target === target3");

function step1() {

  document.scrollingElement.scrollTop = 10000;

  runTestCycle(step2, "document.scrollingElement.scrollTop = 10000");

  assert_equals(entries.length, 4, "Four notifications.");

  assert_equals(entries[3].target, target1, "entries[3].target === target1");

function step2() {

  document.scrollingElement.scrollTop = 0;

  runTestCycle(step3, "document.scrollingElement.scrollTop = 0");

  assert_equals(entries.length, 6, "Six notifications.");

  assert_equals(entries[4].target, target2, "entries[4].target === target2");

  assert_equals(entries[5].target, target3, "entries[5].target === target3");

function step3() {

  assert_equals(entries.length, 9, "Nine notifications.");

  assert_equals(entries[6].target, target1, "entries[6].target === target1");

  assert_equals(entries[7].target, target2, "entries[7].target === target2");

  assert_equals(entries[8].target, target3, "entries[8].target === target3");

</script>