scroll-restoration-order.html

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This test has a WPT meta file that expects 1 subtest issues.
This WPT test may be referenced by the following Test IDs:
- /html/browsers/browsing-the-web/history-traversal/scroll-restoration-order.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<meta charset="utf-8">

<title>History restoration order test</title>

<meta name="assert" content="https://html.spec.whatwg.org/multipage/browsing-the-web.html#history-traversal">

<meta name="assert" content="Traversing history should restore scroll position after dispatching popstate and before dispatching hashchange">

<style>

  body {

    height: 200vh;

    width: 200vw;

</style>

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

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

<script>

  'use strict';

  async_test(function(t) {

    window.addEventListener('load', t.step_func(function() {

      // Allow 1px epsilon for fractional scrolling.

      assert_array_approx_equals(scrollPosition(), [0, 0], 1);

      history.pushState('#1', '', '#1');

      window.scrollTo(50, 100);

      assert_array_approx_equals(scrollPosition(), [50, 100], 1);

      history.pushState('#2', '', '#2');

      window.scrollTo(100, 200);

      assert_array_approx_equals(scrollPosition(), [100, 200], 1);

      setTimeout(t.step_func(function(){

        history.pushState(null, null, '#done');

        window.scrollTo(555, 555);

        assert_array_approx_equals(scrollPosition(), [555, 555], 1);

        // Kick off the verification.

        window.history.back();

      }), 0);

    }));

    window.addEventListener('popstate', t.step_func(function() {

      // Verify that scroll position is *not* restored before popstate.

      const key = location.hash;

      const expected_scroll_position = expectedScrollPositionForKey(key);

      assert_not_equals(scrollPosition()[0], expected_scroll_position[0], `scroll is restored before popstate for ${key}`);

      assert_not_equals(scrollPosition()[1], expected_scroll_position[1], `scroll is restored before popstate for ${key}`);

      if (key == '')

        t.done();

      else

        setTimeout(t.step_func(function(){ window.history.back(); }), 0);

    }));

    window.addEventListener('hashchange', t.step_func(function() {

      // Verify that scroll position is restored before hashchange.

      var key = location.hash;

      const expected_scroll_position = expectedScrollPositionForKey(key);

      assert_array_approx_equals(scrollPosition(), expected_scroll_position, 1, `scroll is restored before hashchange for ${key}`);

    }));

    function scrollPosition() {

      return [window.pageXOffset, window.pageYOffset];

    function expectedScrollPositionForKey(key) {

      switch (key) {

        case '#2': return  [100, 200];

        case '#1': return  [50, 100];

        case ''  : return  [0, 0];

        default: assert_unreached();

  }, 'Traversing history should restore scroll position after dispatching popstate and before dispatching hashchange');

</script>