javascript获取屏幕象素的问题

<script type="text/javascript">
<!--
var winWidth = 0;
var winHeight = 0; 
function findDimensions() //函数：获取尺寸
{//获取窗口宽度
if (window.innerWidth)winWidth = window.innerWidth;
else if ((document.body) && (document.body.clientWidth))winWidth = document.body.clientWidth;//获取窗口高度
if (window.innerHeight)winHeight = window.innerHeight;
else if ((document.body) && (document.body.clientHeight))winHeight = document.body.clientHeight;//通过深入Document内部对body进行检测，获取窗口大小
if (document.documentElement  && document.documentElement.clientHeight && document.documentElement.clientWidth){
winHeight = document.documentElement.clientHeight;
winWidth = document.documentElement.clientWidth;


}//结果输出至两个文本框


}
findDimensions();
//调用函数，获取数值
window.onresize=findDimensions;
//-->
</script>

<div id='Grid' style='overflow-y: auto;' onscroll='scroll()' <script language='javascript'> document.write (' style=height:'+eval(winHeight - 140)+'px; '); </script> >


取数后，我想直接在html出现这个效果

<div id='Grid' style='overflow-y: auto;' onscroll='scroll()' style='he