test_legacy_mouse_events_prevent_default_wheel.html

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<!DOCTYPE HTML>

<html>

<head>

  <meta charset="utf-8">

  <title>PreventDefault on legacy mouse events also default prevents the wheel event</title>

  <script src="/tests/SimpleTest/SimpleTest.js"></script>

  <script src="/tests/SimpleTest/EventUtils.js"></script>

  <link rel="stylesheet" href="/tests/SimpleTest/test.css"/>

  <style>

    body {

      height: 10000px;

  </style>

  <script>

    for (const legacyEvent of ["DOMMouseScroll", "MozMousePixelScroll"]) {

      add_task(async function test() {

        const wheelEventPromise = new Promise(resolve => {

          window.addEventListener("wheel", e => resolve(e), { passive: true, once: true });

})

        window.addEventListener(legacyEvent, e => {

          info(`Prevent default on ${legacyEvent}`);

          e.preventDefault();

        }, { passive: false, once: true });

        const event = {

          deltaMode: WheelEvent.DOM_DELTA_LINE,

          deltaX: -10,

          deltaY: -10,

          lineOrPageDeltaX: -10,

          lineOrPageDeltaY: -10

        info("Synthesize wheel event");

        synthesizeWheel(document.body, 10, 10, event, window);

        info("Waiting for wheel event");

        const wheelEvent = await wheelEventPromise;

        ok(wheelEvent.defaultPrevented, "Wheel was default prevented");

      }, `Default preventing ${legacyEvent} also default prevents wheel`);

  </script>

</head>

<body>

<p id="display"></p>

<div id="content" style="display: none"></div>

<pre id="test"></pre>

</body>

</html>