Created
April 26, 2018 23:57
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Test async getBoundingClientRect with IntersectionObserver vs rAF + gBCR
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<!doctype html> | |
<html lang="en"> | |
<head> | |
<title>Test IntersectionObserver vs rAF + getBoundingClientRect</title> | |
</head> | |
<body> | |
<h1>Test IntersectionObserver vs rAF + getBoundingClientRect</h1> | |
<button type=button onclick=testIO()>Test using IntersectionObserver</button> | |
<button type=button onclick=testGBCR()>Test using rAF + gBCR</button> | |
<pre id=display></pre> | |
<div id="theContainer"></div> | |
<script> | |
function asyncGetBoundingClientRectUsingIO(element) { | |
return new Promise(function (resolve) { | |
var observer = new IntersectionObserver(function (entries) { | |
observer.disconnect(); | |
resolve(entries[0].boundingClientRect); | |
}); | |
observer.observe(element); | |
}) | |
} | |
function asyncGetBoundingClientRectUsingGBCR(element) { | |
return new Promise(function (resolve) { | |
requestAnimationFrame(function () { | |
var rect = element.getBoundingClientRect() | |
resolve(rect) | |
}) | |
}) | |
} | |
function log(str) { | |
display.innerHTML += str + '\n' | |
} | |
var $ = document.querySelector.bind(document) | |
var container = $('#theContainer') | |
function fillContainer() { | |
var bigText = '<table>' | |
for (var i = 0; i < 1000; i++) { | |
bigText += '<tr>' | |
for (var j = 0; j < 10; j++) { | |
bigText += '<td>' + i + ' ' + j + '</td>' | |
} | |
bigText += '</tr>' | |
} | |
bigText += '</table>' | |
container.innerHTML = bigText | |
return Promise.resolve() | |
} | |
function Marker(str) { | |
this.str = str | |
} | |
Marker.prototype.mark = function () { | |
performance.mark('start_' + this.str) | |
} | |
Marker.prototype.stop = function () { | |
performance.mark('end_' + this.str) | |
performance.measure(this.str, 'start_' + this.str, 'end_' + this.str) | |
return performance.getEntriesByName(this.str).reverse().slice(-1)[0].duration | |
} | |
function stringifyRect(rect) { | |
return JSON.stringify({ left: rect.left, top: rect.top, width: rect.width, height: rect.height }) | |
} | |
function testGBCR() { | |
var marker = new Marker('gbcr-' + Math.random()) | |
fillContainer().then(function () { | |
marker.mark() | |
return asyncGetBoundingClientRectUsingGBCR(container) | |
}).then(function (rect) { | |
var duration = marker.stop() | |
log('duration: ' + duration + ', rect: ' + stringifyRect(rect)) | |
container.innerHTML = '' | |
}).catch(console.error.bind(console)) | |
} | |
function testIO() { | |
var marker = new Marker('io-' + Math.random()) | |
fillContainer().then(function () { | |
marker.mark() | |
return asyncGetBoundingClientRectUsingIO(container) | |
}).then(function (rect) { | |
var duration = marker.stop() | |
log('duration: ' + duration + ', rect: ' + stringifyRect(rect)) | |
container.innerHTML = '' | |
}).catch(console.error.bind(console)) | |
} | |
</script> | |
</body> | |
</html> |
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