|  | <!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; | 
|  | } | 
|  | #root { | 
|  | width: 200px; | 
|  | height: 200px; | 
|  | overflow: visible; | 
|  | } | 
|  | #target { | 
|  | background-color: green; | 
|  | } | 
|  | </style> | 
|  |  | 
|  | <div id="root"> | 
|  | <div id="target" style="width: 100px; height: 100px; transform: translateY(250px)"></div> | 
|  | </div> | 
|  |  | 
|  | <script> | 
|  | var entries = []; | 
|  |  | 
|  | runTestCycle(function() { | 
|  | var root = document.getElementById('root'); | 
|  | assert_true(!!root, "root element exists."); | 
|  | var target = document.getElementById('target'); | 
|  | assert_true(!!target, "target element exists."); | 
|  | var observer = new IntersectionObserver(function(changes) { | 
|  | entries = entries.concat(changes); | 
|  | }, { root: root }); | 
|  | observer.observe(target); | 
|  | entries = entries.concat(observer.takeRecords()); | 
|  | assert_equals(entries.length, 0, "No initial notifications."); | 
|  | runTestCycle(step0, "First rAF."); | 
|  | }, "IntersectionObserver should detect and report edge-adjacent and zero-area intersections."); | 
|  |  | 
|  | function step0() { | 
|  | runTestCycle(step1, "Set transform=translateY(200px) on target."); | 
|  | checkLastEntry(entries, 0, [8, 108, 258, 358, 0, 0, 0, 0, 8, 208, 8, 208, false]); | 
|  | target.style.transform = "translateY(200px)"; | 
|  | } | 
|  |  | 
|  | function step1() { | 
|  | runTestCycle(step2, "Set transform=translateY(201px) on target."); | 
|  | checkLastEntry(entries, 1, [8, 108, 208, 308, 8, 108, 208, 208, 8, 208, 8, 208, true]); | 
|  | target.style.transform = "translateY(201px)"; | 
|  | } | 
|  |  | 
|  | function step2() { | 
|  | runTestCycle(step3, "Set transform=translateY(185px) on target."); | 
|  | checkLastEntry(entries, 2); | 
|  | target.style.height = "0px"; | 
|  | target.style.width = "300px"; | 
|  | target.style.transform = "translateY(185px)"; | 
|  | } | 
|  |  | 
|  | function step3() { | 
|  | checkLastEntry(entries, 3, [8, 308, 193, 193, 8, 208, 193, 193, 8, 208, 8, 208, true]); | 
|  | } | 
|  | </script> |