全部用||，可以这么写吗？
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<script type="text/javascript">
var w=document.documentElement.clientWidth||document.body.clientWidth||window.innerWidth;
var h=document.documentElement.clientHeight||document.body.clientHeight||window.innerHeight;
document.write("width；"+w+"px"+"<br/>");
document.write("height："+h+"px");
</script>
</body>
</html>
