src/third_party/web_platform_tests/intersection-observer/zero-area-element-visible.html - cobalt - Git at Google

 <!DOCTYPE html>
 <meta name="viewport" content="width=device-width,initial-scale=1">
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <script src="./resources/intersection-observer-test-utils.js"></script>

 <style>
 pre, #log {
   position: absolute;
   top: 0;
   left: 200px;
 }
 #target {
   width: 0px;
   height: 0px;
 }
 </style>

 <div id='target'></div>

 <script>
 var entries = [];

 runTestCycle(function() {
   var target = document.getElementById('target');
   assert_true(!!target, "target exists");
   var observer = new IntersectionObserver(function(changes) {
     entries = entries.concat(changes)
   });
   observer.observe(target);
   entries = entries.concat(observer.takeRecords());
   assert_equals(entries.length, 0, "No initial notifications.");
   runTestCycle(step0, "First rAF should generate a notification.");
 }, "Ensure that a zero-area target intersecting root generates a notification with intersectionRatio == 1");

 function step0() {
   assert_equals(entries.length, 1, "One notification.");
   assert_equals(entries[0].intersectionRatio, 1, "intersectionRatio == 1");
 }
 </script>
	<!DOCTYPE html>
	<meta name="viewport" content="width=device-width,initial-scale=1">
	<script src="/resources/testharness.js"></script>
	<script src="/resources/testharnessreport.js"></script>
	<script src="./resources/intersection-observer-test-utils.js"></script>

	<style>
	pre, #log {
	position: absolute;
	top: 0;
	left: 200px;
	}
	#target {
	width: 0px;
	height: 0px;
	}
	</style>

	<div id='target'></div>

	<script>
	var entries = [];

	runTestCycle(function() {
	var target = document.getElementById('target');
	assert_true(!!target, "target exists");
	var observer = new IntersectionObserver(function(changes) {
	entries = entries.concat(changes)
	});
	observer.observe(target);
	entries = entries.concat(observer.takeRecords());
	assert_equals(entries.length, 0, "No initial notifications.");
	runTestCycle(step0, "First rAF should generate a notification.");
	}, "Ensure that a zero-area target intersecting root generates a notification with intersectionRatio == 1");

	function step0() {
	assert_equals(entries.length, 1, "One notification.");
	assert_equals(entries[0].intersectionRatio, 1, "intersectionRatio == 1");
	}
	</script>