selection/textcontrols/onselectionchange-content-attribute.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>Test that setting "onselectionchange" content attribute adds an event listener</title>
<link rel="help" href="https://w3c.github.io/selection-api/#extensions-to-globaleventhandlers-interface">

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

<body>
<div id="testElement" onselectionchange="window.handlerSetFromParserWasFired()"></div>
<script>
  promise_test(() => {
    return new Promise(resolve => {
      window.handlerSetFromParserWasFired = resolve;
      testElement.dispatchEvent(new Event("selectionchange"));
    });
  }, "handler set from parser");

  promise_test(() => {
    const el = document.createElement("div");
    el.setAttribute("onselectionchange", "window.handlerSetViaSetAttributeWasFired()");
    document.body.append(el);

    return new Promise(resolve => {
      window.handlerSetViaSetAttributeWasFired = resolve;
      el.dispatchEvent(new Event("selectionchange"));
    });
  }, "handler set via setAttribute()");
</script>