focus/ancestor-activeelement-after-child-lose-focus.html

<!doctype html>
<head>
<meta charset=utf-8>
<title>Ancestor's activeElement should be cleared when child loses focus</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
</head>
<body>
<input placeholder="input in top level"/>
<iframe srcdoc="<iframe srcdoc='<input>'></iframe>"></iframe>
<script>
const outerIFrame = document.querySelector('iframe');
function runTest() {
  test(() => {
    assert_true(outerIFrame.contentDocument.activeElement === outerIFrame.contentDocument.body,
      "Initially, the activeElement of the outer iframe should be <body>");

    const innerIFrame = outerIFrame.contentDocument.querySelector("iframe");
    const inputInInner = innerIFrame.contentDocument.querySelector('input');

    // Now we focus the input in the inner iframe
    inputInInner.focus();
    // outerIframe is the ancestor of inner iframe, so the activeElement of
    // it should be the inner iframe.
    assert_true(outerIFrame.contentDocument.activeElement === innerIFrame,
      "The activeElement of the outer iframe should be the inner iframe");

    // Now we focus the input in the top level
    document.querySelector("input").focus();
    // Since inner iframe lost its focus, the activeElement of outer iframe
    // should be cleared as well, hence <body> should be focused.
    assert_true(outerIFrame.contentDocument.activeElement === outerIFrame.contentDocument.body,
      "The activeElement of the outer iframe should be reverted back to <body>");

    assert_true(document.activeElement === document.querySelector("input"),
      "The activeElement of the top-level document should be the input");
  });
}

window.onload = function() {
  runTest();
}
</script>
</body>