JS获取浏览器窗口的宽度和高度

<script type="text/javascript">
<!--

var viewportwidth;
var viewportheight;

// the more standards compliant browsers (mozilla/netscape/opera/IE7) use window.innerWidth and window.innerHeight

if (typeof window.innerWidth != 'undefined')
{
viewportwidth = window.innerWidth,
viewportheight = window.innerHeight
}

// IE6 in standards compliant mode (i.e. with a valid doctype as the first line in the document)

else if (typeof document.documentElement != 'undefined'
&& typeof document.documentElement.clientWidth !=
'undefined' && document.documentElement.clientWidth != 0)
{
viewportwidth = document.documentElement.clientWidth,
viewportheight = document.documentElement.clientHeight
}

// older versions of IE

else
{
viewportwidth = document.getElementsByTagName('body')[0].clientWidth,
viewportheight = document.getElementsByTagName('body')[0].clientHeight
}
document.write('<p>Your viewport width is '+viewportwidth+'x'+viewportheight+'</p>');
//-->
</script>