GettingToKnowMutationObservers/mutationobserver-docfrag.html at master · webinista/GettingToKnowMutationObservers · GitHub

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<!DOCTYPE html>
<html lang="en-us">
<head>
	<meta charset="utf-8" />
	<title>Observing a document fragment</title>
	<link rel="stylesheet" href="mutationobserver.css">
</head>
<body>
<header>
	<h1>Observing the addition of nodes to a document fragment.</h1>
	<nav><a href="http://dev.opera.com/articles/view/mutation-observers-tutorial/">Return to article</a></nav>
</header>

<article>
	<p>In this example, we're going to watch for updates to a document fragment. Using a document fragment is a way of batching DOM additions into one update. Clicking the <b>Add paragraphs</b> button will append the document fragment. Clicking the <b>Add to body</b> button will add the document fragment to the document's body.</p>

	<p><b class="numevents">0</b> mutation(s) occurred.</p>

	<p>
	 <button type="button">Add paragraphs</button>
	 <button type="button">Add to body</button>
	</p>
</article>

<div id="demo"></div>

<script>
(function(d){
	var thismany = 1000,
	btn = d.querySelectorAll('button'),
	demo = d.getElementById('demo'),
	docfrag = d.createDocumentFragment()
	clickhandler = function(){
		var i = 0,
		n = thismany,
		p,
		sentence = 'Lorem ipsum dolar sit amet consecutum.';

		while( i < n ){
			p = (p !== undefined) ? p = p.cloneNode(true) : p = d.createElement('p');
			if(!p.textContent){ p.textContent = sentence; }
			docfrag.appendChild(p);
			i++;
		}

	}
	btn[0].addEventListener('click',clickhandler,false);
	btn[1].addEventListener('click',function(){
		demo.appendChild(docfrag);
	},false);

	var mocallback = function(mr){
		d.querySelector('.numevents').textContent = mr.length;
		mo.takeRecords();
	},
	mo = new MutationObserver(mocallback);
	mo.observe(docfrag,{'childList':true,'subtree':true});
})(document);
</script>

</body>
</html>