intersection-observer/document-scrolling-element-root.html

<!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;
}
iframe {
  height: 250px;
  width: 150px;
  border: 0;
}
</style>
<iframe id="target-iframe" src="resources/iframe-no-root-subframe.html"></iframe>

<script>
var iframe = document.getElementById("target-iframe");
var target;
var root;
var entries = [];

iframe.onload = function() {
  runTestCycle(function() {
    assert_true(!!iframe, "iframe exists");

    target = iframe.contentDocument.getElementById("target");
    assert_true(!!target, "Target element exists.");
    var observer = new IntersectionObserver(function(changes) {
      entries = entries.concat(changes)
    }, { root: iframe.contentDocument });
    observer.observe(target);
    entries = entries.concat(observer.takeRecords());
    assert_equals(entries.length, 0, "No initial notifications.");
    runTestCycle(step0, "First rAF.");
  }, "Observer with explicit root which is the document.");
};

function step0() {
  let vw = iframe.contentDocument.documentElement.clientWidth;
  let vh = iframe.contentDocument.documentElement.clientHeight;
  // The target element is partially clipped by the iframe's root scroller, so
  // height of the intersection rect is (250 - 208) == 42.
  checkLastEntry(entries, 0, [8, 108, 208, 308, 8, 108, 208, 250, 0, vw, 0, vh, true]);
}
</script>