javascript如何删除页面内容？

ie6 测试通过
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>createRange测试</title>
<script type="text/javascript">
function WD(){
document.selection.createRange().text="";
}
</script>
</head>
<body>
afffffffffffffffffffffffffffffefe<br>
afffffffffffffffffffffffffffffefe<br>
afffffffffffffffffffffffffffffefe<br>
afffffffffffffffffffffffffffffefe<br>
afffffffffffffffffffffffffffffefe<br>
afffffffffffffffffffffffffffffefe
<input type='button' value='删除' onclick='WD()'/>
</body>
</html>