domfarolino/asyncForEach.js

## asyncForEach.js
const array = [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1];

function handleArrayValue(v) {
	console.log(`Handling ${v}`);
	for (let i = 0; i < 15000; ++i) {
  	for (let j = 0; j < i; ++j) {
    	// Nothing!
    }
  }
}

function asyncForEach(cb) {
	this.forEach(v => {
  	setTimeout(_ => {
    	cb(v);
    }, 0);
  });
}

Array.prototype.asyncForEach = asyncForEach;

document.querySelector('#asyncTrigger').addEventListener('click', evt => {
  array.asyncForEach(handleArrayValue);
});

document.querySelector('#syncTrigger').addEventListener('click', evt => {
  array.forEach(handleArrayValue);
});

## index.html
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Async For Each</title>
    <link rel="stylesheet" href="master.css">
    <link href="https://fonts.googleapis.com/icon?family=Roboto" rel="stylesheet">
  </head>
  <body>
    <h1>UI Render Blocking Example</h1>
    <div id="expander"></div>
    <div id="lorem">
      <button id="syncTrigger" type="button" name="button">Synchronous <code>.forEach(...)</code></button>
      <button id="asyncTrigger" type="button" name="button">Asynchronous <code>.forEach(...)</code></button>
      <p style="margin-top: 10px">
        "Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium,
        totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta
        sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia
        consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui
        dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora
        incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum
        exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem
        vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui
        dolorem eum fugiat quo voluptas nulla pariatur?"
      </p>
    </div>

    <script src="asyncForEach.js" defer></script>
  </body>
</html>

## master.css
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: Roboto, sans-serif;
}

h1 {
  text-align: center;
}

#expander {
  background: firebrick;
  width: 200px;
  height: 200px;
  margin: 80px auto;
  transition: transform 2s;
}

#expander:hover {
  transform: rotate(180deg);
}

#lorem {
  width:90%;
  max-width: 500px;
  margin: 0 auto
}

button {
  padding: 10px;
}
	const array = [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1];

	function handleArrayValue(v) {
	console.log(`Handling ${v}`);
	for (let i = 0; i < 15000; ++i) {
	for (let j = 0; j < i; ++j) {
	// Nothing!
	}
	}
	}

	function asyncForEach(cb) {
	this.forEach(v => {
	setTimeout(_ => {
	cb(v);
	}, 0);
	});
	}

	Array.prototype.asyncForEach = asyncForEach;

	document.querySelector('#asyncTrigger').addEventListener('click', evt => {
	array.asyncForEach(handleArrayValue);
	});

	document.querySelector('#syncTrigger').addEventListener('click', evt => {
	array.forEach(handleArrayValue);
	});
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8">
	<title>Async For Each</title>
	<link rel="stylesheet" href="master.css">
	<link href="https://fonts.googleapis.com/icon?family=Roboto" rel="stylesheet">
	</head>
	<body>
	<h1>UI Render Blocking Example</h1>
	<div id="expander"></div>
	<div id="lorem">
	<button id="syncTrigger" type="button" name="button">Synchronous <code>.forEach(...)</code></button>
	<button id="asyncTrigger" type="button" name="button">Asynchronous <code>.forEach(...)</code></button>
	<p style="margin-top: 10px">
	"Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium,
	totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta
	sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia
	consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui
	dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora
	incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum
	exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem
	vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui
	dolorem eum fugiat quo voluptas nulla pariatur?"
	</p>
	</div>

	<script src="asyncForEach.js" defer></script>
	</body>
	</html>
	* {
	margin: 0;
	padding: 0;
	box-sizing: border-box;
	font-family: Roboto, sans-serif;
	}

	h1 {
	text-align: center;
	}

	#expander {
	background: firebrick;
	width: 200px;
	height: 200px;
	margin: 80px auto;
	transition: transform 2s;
	}

	#expander:hover {
	transform: rotate(180deg);
	}

	#lorem {
	width:90%;
	max-width: 500px;
	margin: 0 auto
	}

	button {
	padding: 10px;
	}