third_party/blink/web_tests/external/wpt/scroll-animations/current-time.html - chromium/src - Git at Google

 <!DOCTYPE html>
 <meta charset="utf-8">
 <title>ScrollTimeline current time algorithm</title>
 <link rel="help" href="https://wicg.github.io/scroll-animations/#current-time-algorithm">
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>

 <script src="./resources/scrolltimeline-utils.js"></script>

 <body></body>

 <script>
 'use strict';

 test(function() {
   const scroller = setupScrollTimelineTest();
   // Set the timeRange such that currentTime maps directly to the value
   // scrolled. The contents and scroller are square, so it suffices to compute
   // one edge and use it for all the timelines.
   const scrollerSize = scroller.scrollHeight - scroller.clientHeight;

   const blockScrollTimeline = new ScrollTimeline(
       {scrollSource: scroller, timeRange: scrollerSize, orientation: 'block'});
   const inlineScrollTimeline = new ScrollTimeline(
       {scrollSource: scroller, timeRange: scrollerSize, orientation: 'inline'});
   const horizontalScrollTimeline = new ScrollTimeline({
     scrollSource: scroller,
     timeRange: scrollerSize,
     orientation: 'horizontal'
   });
   const verticalScrollTimeline = new ScrollTimeline({
     scrollSource: scroller,
     timeRange: scrollerSize,
     orientation: 'vertical'
   });

   // Unscrolled, all timelines should read a currentTime of 0.
   assert_equals(
       blockScrollTimeline.currentTime, 0, 'Unscrolled block timeline');
   assert_equals(
       inlineScrollTimeline.currentTime, 0, 'Unscrolled inline timeline');
   assert_equals(
       horizontalScrollTimeline.currentTime, 0,
       'Unscrolled horizontal timeline');
   assert_equals(
       verticalScrollTimeline.currentTime, 0, 'Unscrolled vertical timeline');

   // Do some scrolling and make sure that the ScrollTimelines update.
   scroller.scrollTop = 50;
   scroller.scrollLeft = 75;

   // As noted above timeRange is mapped such that currentTime should be the
   // scroll offset.
   assert_equals(blockScrollTimeline.currentTime, 50, 'Scrolled block timeline');
   assert_equals(
       inlineScrollTimeline.currentTime, 75, 'Scrolled inline timeline');
   assert_equals(
       horizontalScrollTimeline.currentTime, 75, 'Scrolled horizontal timeline');
   assert_equals(
       verticalScrollTimeline.currentTime, 50, 'Scrolled vertical timeline');
 }, 'currentTime calculates the correct time based on scrolled amount');

 test(function() {
   // It is difficult to calculate the scroll offset which results in an exact
   // currentTime. Scrolling is calculated in integers which allows for the
   // possibility of rounding, and scrollbar widths differ between platforms
   // which means it is not possible to ensure a divisible scroller size. Instead
   // the scroller content is made large enough that rounding differences result
   // in negligible deltas in the output value.
   const contentOverrides = new Map([['width', '1000px'], ['height', '1000px']]);
   const scroller = setupScrollTimelineTest(new Map(), contentOverrides);
   const scrollTimeline = new ScrollTimeline(
       {scrollSource: scroller, timeRange: 100, orientation: 'block'});

   // Mapping timeRange to 100 means the output is 'percentage scrolled', so
   // calculate where the 50% scroll mark would be.
   const halfwayY = (scroller.scrollHeight - scroller.clientHeight) / 2;
   scroller.scrollTop = halfwayY;

   assert_approx_equals(scrollTimeline.currentTime, 50, 0.5);
 }, 'currentTime adjusts correctly for the timeRange');

 test(function() {
   const scroller = setupScrollTimelineTest();
   // Set the timeRange such that currentTime maps directly to the value
   // scrolled. The contents and scroller are square, so it suffices to compute
   // one edge and use it for all the timelines.
   const scrollerSize = scroller.scrollHeight - scroller.clientHeight;

   const lengthScrollTimeline = new ScrollTimeline({
     scrollSource: scroller,
     timeRange: scrollerSize,
     orientation: 'block',
     startScrollOffset: '20px'
   });
   const percentageScrollTimeline = new ScrollTimeline({
     scrollSource: scroller,
     timeRange: scrollerSize,
     orientation: 'block',
     startScrollOffset: '20%'
   });
   const calcScrollTimeline = new ScrollTimeline({
     scrollSource: scroller,
     timeRange: scrollerSize,
     orientation: 'block',
     startScrollOffset: 'calc(20% - 5px)'
   });

   // Unscrolled all timelines should read a current time of unresolved, as the
   // current offset (0) will be less than the startScrollOffset.
   assert_equals(
       lengthScrollTimeline.currentTime, null,
       'Unscrolled length-based timeline');
   assert_equals(
       percentageScrollTimeline.currentTime, null,
       'Unscrolled percentage-based timeline');
   assert_equals(
       calcScrollTimeline.currentTime, null, 'Unscrolled calc-based timeline');

   // Check the length-based ScrollTimeline.
   scroller.scrollTop = 19;
   assert_equals(
       lengthScrollTimeline.currentTime, null,
       'Length-based timeline before the startScrollOffset point');
   scroller.scrollTop = 20;
   assert_equals(
       lengthScrollTimeline.currentTime, 0,
       'Length-based timeline at the startScrollOffset point');
   scroller.scrollTop = 50;
   assert_equals(
       lengthScrollTimeline.currentTime,
       calculateCurrentTime(50, 20, scrollerSize, scrollerSize),
       'Length-based timeline after the startScrollOffsetPoint');

   // Check the percentage-based ScrollTimeline.
   scroller.scrollTop = 0.19 * scrollerSize;
   assert_equals(
       percentageScrollTimeline.currentTime, null,
       'Percentage-based scroller before the startScrollOffset point');
   scroller.scrollTop = 0.20 * scrollerSize;
   assert_equals(
       percentageScrollTimeline.currentTime, 0,
       'Percentage-based scroller at the startScrollOffset point');
   scroller.scrollTop = 0.50 * scrollerSize;
   assert_equals(
       percentageScrollTimeline.currentTime,
       calculateCurrentTime(
           scroller.scrollTop, 0.2 * scrollerSize, scrollerSize, scrollerSize),
       'Percentage-based scroller after the startScrollOffset point');

   // Check the calc-based ScrollTimeline.
   scroller.scrollTop = 0.2 * scrollerSize - 10;
   assert_equals(
       calcScrollTimeline.currentTime, null,
       'Calc-based scroller before the startScrollOffset point');
   scroller.scrollTop = 0.2 * scrollerSize - 5;
   assert_equals(
       calcScrollTimeline.currentTime, 0,
       'Calc-based scroller at the startScrollOffset point');
   scroller.scrollTop = 0.2 * scrollerSize;
   assert_equals(
       calcScrollTimeline.currentTime,
       calculateCurrentTime(
           scroller.scrollTop, 0.2 * scrollerSize - 5, scrollerSize,
           scrollerSize),
       'Calc-based scroller after the startScrollOffset point');
 }, 'currentTime handles startScrollOffset correctly');

 test(function() {
   const scroller = setupScrollTimelineTest();
   // Set the timeRange such that currentTime maps directly to the value
   // scrolled. The contents and scroller are square, so it suffices to compute
   // one edge and use it for all the timelines.
   const scrollerSize = scroller.scrollHeight - scroller.clientHeight;

   const lengthScrollTimeline = new ScrollTimeline({
     scrollSource: scroller,
     timeRange: scrollerSize,
     orientation: 'block',
     endScrollOffset: (scrollerSize - 20) + 'px'
   });
   const percentageScrollTimeline = new ScrollTimeline({
     scrollSource: scroller,
     timeRange: scrollerSize,
     orientation: 'block',
     endScrollOffset: '80%'
   });
   const calcScrollTimeline = new ScrollTimeline({
     scrollSource: scroller,
     timeRange: scrollerSize,
     orientation: 'block',
     endScrollOffset: 'calc(80% + 5px)'
   });

   // Check the length-based ScrollTimeline.
   scroller.scrollTop = scrollerSize;
   assert_equals(
       lengthScrollTimeline.currentTime, null,
       'Length-based timeline after the endScrollOffset point');
   scroller.scrollTop = scrollerSize - 20;
   assert_equals(
       lengthScrollTimeline.currentTime,
       calculateCurrentTime(
           scrollerSize - 20, 0, scrollerSize - 20, scrollerSize),
       'Length-based timeline at the endScrollOffset point');
   scroller.scrollTop = scrollerSize - 50;
   assert_equals(
       lengthScrollTimeline.currentTime,
       calculateCurrentTime(
           scrollerSize - 50, 0, scrollerSize - 20, scrollerSize),
       'Length-based timeline before the endScrollOffset point');

   // Check the percentage-based ScrollTimeline.
   scroller.scrollTop = 0.81 * scrollerSize;
   assert_equals(
       percentageScrollTimeline.currentTime, null,
       'Percentage-based timeline after the endScrollOffset point');
   scroller.scrollTop = 0.80 * scrollerSize;
   assert_equals(
       percentageScrollTimeline.currentTime,
       calculateCurrentTime(
           scroller.scrollTop, 0, 0.8 * scrollerSize, scrollerSize),
       'Percentage-based timeline at the endScrollOffset point');
   scroller.scrollTop = 0.50 * scrollerSize;
   assert_equals(
       percentageScrollTimeline.currentTime,
       calculateCurrentTime(
           scroller.scrollTop, 0, 0.8 * scrollerSize, scrollerSize),
       'Percentage-based timeline before the endScrollOffset point');

   // Check the calc-based ScrollTimeline.
   scroller.scrollTop = 0.8 * scrollerSize + 6;
   assert_equals(
       calcScrollTimeline.currentTime, null,
       'Calc-based timeline after the endScrollOffset point');
   scroller.scrollTop = 0.8 * scrollerSize + 5;
   assert_equals(
       calcScrollTimeline.currentTime,
       calculateCurrentTime(
           scroller.scrollTop, 0, 0.8 * scrollerSize + 5, scrollerSize),
       'Calc-based timeline at the endScrollOffset point');
   scroller.scrollTop = 0.5 * scrollerSize;
   assert_equals(
       calcScrollTimeline.currentTime,
       calculateCurrentTime(
           scroller.scrollTop, 0, 0.8 * scrollerSize + 5, scrollerSize),
       'Calc-based timeline before the endScrollOffset point');
 }, 'currentTime handles endScrollOffset correctly');

 test(function() {
   const scroller = setupScrollTimelineTest();
   // Set the timeRange such that currentTime maps directly to the value
   // scrolled. The contents and scroller are square, so it suffices to compute
   // one edge and use it for all the timelines.
   const scrollerSize = scroller.scrollHeight - scroller.clientHeight;

   const scrollTimeline = new ScrollTimeline({
     scrollSource: scroller,
     timeRange: scrollerSize,
     orientation: 'block',
     startScrollOffset: '20px',
     endScrollOffset: (scrollerSize - 50) + 'px'
   });

   scroller.scrollTop = 150;
   assert_equals(
       scrollTimeline.currentTime,
       calculateCurrentTime(150, 20, scrollerSize - 50, scrollerSize));
 }, 'currentTime handles startScrollOffset and endScrollOffset together correctly');

 test(function() {
   const scroller = setupScrollTimelineTest();
   // Set the timeRange such that currentTime maps directly to the value
   // scrolled. The contents and scroller are square, so it suffices to compute
   // one edge and use it for all the timelines.
   const scrollerSize = scroller.scrollHeight - scroller.clientHeight;

   const scrollTimeline = new ScrollTimeline({
     scrollSource: scroller,
     timeRange: scrollerSize,
     orientation: 'block',
     startScrollOffset: '20px',
     endScrollOffset: '20px',
   });

   scroller.scrollTop = 150;
   assert_equals(scrollTimeline.currentTime, null);
 }, 'currentTime handles startScrollOffset == endScrollOffset correctly');

 test(function() {
   const scroller = setupScrollTimelineTest();
   // Set the timeRange such that currentTime maps directly to the value
   // scrolled. The contents and scroller are square, so it suffices to compute
   // one edge and use it for all the timelines.
   const scrollerSize = scroller.scrollHeight - scroller.clientHeight;

   const scrollTimeline = new ScrollTimeline({
     scrollSource: scroller,
     timeRange: scrollerSize,
     orientation: 'block',
     startScrollOffset: '50px',
     endScrollOffset: '10px',
   });

   scroller.scrollTop = 150;
   assert_equals(scrollTimeline.currentTime, null);
 }, 'currentTime handles startScrollOffset > endScrollOffset correctly');
 </script>
	<!DOCTYPE html>
	<meta charset="utf-8">
	<title>ScrollTimeline current time algorithm</title>
	<link rel="help" href="https://wicg.github.io/scroll-animations/#current-time-algorithm">
	<script src="/resources/testharness.js"></script>
	<script src="/resources/testharnessreport.js"></script>

	<script src="./resources/scrolltimeline-utils.js"></script>

	<body></body>

	<script>
	'use strict';

	test(function() {
	const scroller = setupScrollTimelineTest();
	// Set the timeRange such that currentTime maps directly to the value
	// scrolled. The contents and scroller are square, so it suffices to compute
	// one edge and use it for all the timelines.
	const scrollerSize = scroller.scrollHeight - scroller.clientHeight;

	const blockScrollTimeline = new ScrollTimeline(
	{scrollSource: scroller, timeRange: scrollerSize, orientation: 'block'});
	const inlineScrollTimeline = new ScrollTimeline(
	{scrollSource: scroller, timeRange: scrollerSize, orientation: 'inline'});
	const horizontalScrollTimeline = new ScrollTimeline({
	scrollSource: scroller,
	timeRange: scrollerSize,
	orientation: 'horizontal'
	});
	const verticalScrollTimeline = new ScrollTimeline({
	scrollSource: scroller,
	timeRange: scrollerSize,
	orientation: 'vertical'
	});

	// Unscrolled, all timelines should read a currentTime of 0.
	assert_equals(
	blockScrollTimeline.currentTime, 0, 'Unscrolled block timeline');
	assert_equals(
	inlineScrollTimeline.currentTime, 0, 'Unscrolled inline timeline');
	assert_equals(
	horizontalScrollTimeline.currentTime, 0,
	'Unscrolled horizontal timeline');
	assert_equals(
	verticalScrollTimeline.currentTime, 0, 'Unscrolled vertical timeline');

	// Do some scrolling and make sure that the ScrollTimelines update.
	scroller.scrollTop = 50;
	scroller.scrollLeft = 75;

	// As noted above timeRange is mapped such that currentTime should be the
	// scroll offset.
	assert_equals(blockScrollTimeline.currentTime, 50, 'Scrolled block timeline');
	assert_equals(
	inlineScrollTimeline.currentTime, 75, 'Scrolled inline timeline');
	assert_equals(
	horizontalScrollTimeline.currentTime, 75, 'Scrolled horizontal timeline');
	assert_equals(
	verticalScrollTimeline.currentTime, 50, 'Scrolled vertical timeline');
	}, 'currentTime calculates the correct time based on scrolled amount');

	test(function() {
	// It is difficult to calculate the scroll offset which results in an exact
	// currentTime. Scrolling is calculated in integers which allows for the
	// possibility of rounding, and scrollbar widths differ between platforms
	// which means it is not possible to ensure a divisible scroller size. Instead
	// the scroller content is made large enough that rounding differences result
	// in negligible deltas in the output value.
	const contentOverrides = new Map([['width', '1000px'], ['height', '1000px']]);
	const scroller = setupScrollTimelineTest(new Map(), contentOverrides);
	const scrollTimeline = new ScrollTimeline(
	{scrollSource: scroller, timeRange: 100, orientation: 'block'});

	// Mapping timeRange to 100 means the output is 'percentage scrolled', so
	// calculate where the 50% scroll mark would be.
	const halfwayY = (scroller.scrollHeight - scroller.clientHeight) / 2;
	scroller.scrollTop = halfwayY;

	assert_approx_equals(scrollTimeline.currentTime, 50, 0.5);
	}, 'currentTime adjusts correctly for the timeRange');

	test(function() {
	const scroller = setupScrollTimelineTest();
	// Set the timeRange such that currentTime maps directly to the value
	// scrolled. The contents and scroller are square, so it suffices to compute
	// one edge and use it for all the timelines.
	const scrollerSize = scroller.scrollHeight - scroller.clientHeight;

	const lengthScrollTimeline = new ScrollTimeline({
	scrollSource: scroller,
	timeRange: scrollerSize,
	orientation: 'block',
	startScrollOffset: '20px'
	});
	const percentageScrollTimeline = new ScrollTimeline({
	scrollSource: scroller,
	timeRange: scrollerSize,
	orientation: 'block',
	startScrollOffset: '20%'
	});
	const calcScrollTimeline = new ScrollTimeline({
	scrollSource: scroller,
	timeRange: scrollerSize,
	orientation: 'block',
	startScrollOffset: 'calc(20% - 5px)'
	});

	// Unscrolled all timelines should read a current time of unresolved, as the
	// current offset (0) will be less than the startScrollOffset.
	assert_equals(
	lengthScrollTimeline.currentTime, null,
	'Unscrolled length-based timeline');
	assert_equals(
	percentageScrollTimeline.currentTime, null,
	'Unscrolled percentage-based timeline');
	assert_equals(
	calcScrollTimeline.currentTime, null, 'Unscrolled calc-based timeline');

	// Check the length-based ScrollTimeline.
	scroller.scrollTop = 19;
	assert_equals(
	lengthScrollTimeline.currentTime, null,
	'Length-based timeline before the startScrollOffset point');
	scroller.scrollTop = 20;
	assert_equals(
	lengthScrollTimeline.currentTime, 0,
	'Length-based timeline at the startScrollOffset point');
	scroller.scrollTop = 50;
	assert_equals(
	lengthScrollTimeline.currentTime,
	calculateCurrentTime(50, 20, scrollerSize, scrollerSize),
	'Length-based timeline after the startScrollOffsetPoint');

	// Check the percentage-based ScrollTimeline.
	scroller.scrollTop = 0.19 * scrollerSize;
	assert_equals(
	percentageScrollTimeline.currentTime, null,
	'Percentage-based scroller before the startScrollOffset point');
	scroller.scrollTop = 0.20 * scrollerSize;
	assert_equals(
	percentageScrollTimeline.currentTime, 0,
	'Percentage-based scroller at the startScrollOffset point');
	scroller.scrollTop = 0.50 * scrollerSize;
	assert_equals(
	percentageScrollTimeline.currentTime,
	calculateCurrentTime(
	scroller.scrollTop, 0.2 * scrollerSize, scrollerSize, scrollerSize),
	'Percentage-based scroller after the startScrollOffset point');

	// Check the calc-based ScrollTimeline.
	scroller.scrollTop = 0.2 * scrollerSize - 10;
	assert_equals(
	calcScrollTimeline.currentTime, null,
	'Calc-based scroller before the startScrollOffset point');
	scroller.scrollTop = 0.2 * scrollerSize - 5;
	assert_equals(
	calcScrollTimeline.currentTime, 0,
	'Calc-based scroller at the startScrollOffset point');
	scroller.scrollTop = 0.2 * scrollerSize;
	assert_equals(
	calcScrollTimeline.currentTime,
	calculateCurrentTime(
	scroller.scrollTop, 0.2 * scrollerSize - 5, scrollerSize,
	scrollerSize),
	'Calc-based scroller after the startScrollOffset point');
	}, 'currentTime handles startScrollOffset correctly');

	test(function() {
	const scroller = setupScrollTimelineTest();
	// Set the timeRange such that currentTime maps directly to the value
	// scrolled. The contents and scroller are square, so it suffices to compute
	// one edge and use it for all the timelines.
	const scrollerSize = scroller.scrollHeight - scroller.clientHeight;

	const lengthScrollTimeline = new ScrollTimeline({
	scrollSource: scroller,
	timeRange: scrollerSize,
	orientation: 'block',
	endScrollOffset: (scrollerSize - 20) + 'px'
	});
	const percentageScrollTimeline = new ScrollTimeline({
	scrollSource: scroller,
	timeRange: scrollerSize,
	orientation: 'block',
	endScrollOffset: '80%'
	});
	const calcScrollTimeline = new ScrollTimeline({
	scrollSource: scroller,
	timeRange: scrollerSize,
	orientation: 'block',
	endScrollOffset: 'calc(80% + 5px)'
	});

	// Check the length-based ScrollTimeline.
	scroller.scrollTop = scrollerSize;
	assert_equals(
	lengthScrollTimeline.currentTime, null,
	'Length-based timeline after the endScrollOffset point');
	scroller.scrollTop = scrollerSize - 20;
	assert_equals(
	lengthScrollTimeline.currentTime,
	calculateCurrentTime(
	scrollerSize - 20, 0, scrollerSize - 20, scrollerSize),
	'Length-based timeline at the endScrollOffset point');
	scroller.scrollTop = scrollerSize - 50;
	assert_equals(
	lengthScrollTimeline.currentTime,
	calculateCurrentTime(
	scrollerSize - 50, 0, scrollerSize - 20, scrollerSize),
	'Length-based timeline before the endScrollOffset point');

	// Check the percentage-based ScrollTimeline.
	scroller.scrollTop = 0.81 * scrollerSize;
	assert_equals(
	percentageScrollTimeline.currentTime, null,
	'Percentage-based timeline after the endScrollOffset point');
	scroller.scrollTop = 0.80 * scrollerSize;
	assert_equals(
	percentageScrollTimeline.currentTime,
	calculateCurrentTime(
	scroller.scrollTop, 0, 0.8 * scrollerSize, scrollerSize),
	'Percentage-based timeline at the endScrollOffset point');
	scroller.scrollTop = 0.50 * scrollerSize;
	assert_equals(
	percentageScrollTimeline.currentTime,
	calculateCurrentTime(
	scroller.scrollTop, 0, 0.8 * scrollerSize, scrollerSize),
	'Percentage-based timeline before the endScrollOffset point');

	// Check the calc-based ScrollTimeline.
	scroller.scrollTop = 0.8 * scrollerSize + 6;
	assert_equals(
	calcScrollTimeline.currentTime, null,
	'Calc-based timeline after the endScrollOffset point');
	scroller.scrollTop = 0.8 * scrollerSize + 5;
	assert_equals(
	calcScrollTimeline.currentTime,
	calculateCurrentTime(
	scroller.scrollTop, 0, 0.8 * scrollerSize + 5, scrollerSize),
	'Calc-based timeline at the endScrollOffset point');
	scroller.scrollTop = 0.5 * scrollerSize;
	assert_equals(
	calcScrollTimeline.currentTime,
	calculateCurrentTime(
	scroller.scrollTop, 0, 0.8 * scrollerSize + 5, scrollerSize),
	'Calc-based timeline before the endScrollOffset point');
	}, 'currentTime handles endScrollOffset correctly');

	test(function() {
	const scroller = setupScrollTimelineTest();
	// Set the timeRange such that currentTime maps directly to the value
	// scrolled. The contents and scroller are square, so it suffices to compute
	// one edge and use it for all the timelines.
	const scrollerSize = scroller.scrollHeight - scroller.clientHeight;

	const scrollTimeline = new ScrollTimeline({
	scrollSource: scroller,
	timeRange: scrollerSize,
	orientation: 'block',
	startScrollOffset: '20px',
	endScrollOffset: (scrollerSize - 50) + 'px'
	});

	scroller.scrollTop = 150;
	assert_equals(
	scrollTimeline.currentTime,
	calculateCurrentTime(150, 20, scrollerSize - 50, scrollerSize));
	}, 'currentTime handles startScrollOffset and endScrollOffset together correctly');

	test(function() {
	const scroller = setupScrollTimelineTest();
	// Set the timeRange such that currentTime maps directly to the value
	// scrolled. The contents and scroller are square, so it suffices to compute
	// one edge and use it for all the timelines.
	const scrollerSize = scroller.scrollHeight - scroller.clientHeight;

	const scrollTimeline = new ScrollTimeline({
	scrollSource: scroller,
	timeRange: scrollerSize,
	orientation: 'block',
	startScrollOffset: '20px',
	endScrollOffset: '20px',
	});

	scroller.scrollTop = 150;
	assert_equals(scrollTimeline.currentTime, null);
	}, 'currentTime handles startScrollOffset == endScrollOffset correctly');

	test(function() {
	const scroller = setupScrollTimelineTest();
	// Set the timeRange such that currentTime maps directly to the value
	// scrolled. The contents and scroller are square, so it suffices to compute
	// one edge and use it for all the timelines.
	const scrollerSize = scroller.scrollHeight - scroller.clientHeight;

	const scrollTimeline = new ScrollTimeline({
	scrollSource: scroller,
	timeRange: scrollerSize,
	orientation: 'block',
	startScrollOffset: '50px',
	endScrollOffset: '10px',
	});

	scroller.scrollTop = 150;
	assert_equals(scrollTimeline.currentTime, null);
	}, 'currentTime handles startScrollOffset > endScrollOffset correctly');
	</script>