<html>
<head>
<title>Data Properties Example</title>
<script type="text/javascript">
var person = {};
Object.defineProperty(person, "name", {
configurable: false,
value: "Nicholas"
});
alert(person.name);
delete person.name;
alert(person.name);
</script>
</head>
<body>
<p>Note: this example only works in browsers that have implemented the ECMAScript 5 <code>Object.defineProperty()</code> method (IE9 and Firefox 4).</p>
</body>
</html>