覆盖整个页面的div

<style type="text/css">
#shadowDiv {
 display: none;
 width: 100%;
 height: 100%;
 position: absolute;
 top: 0px : left : 0px;
 background-color: #FFF;
 filter: alpha(opacity = 70);
 opacity: 0.7;
 z-index: 65534
}
</style>
<script >
window.onload=function test(){
  var d = document.createElement("DIV");
  d.id = "shadowDiv";
  document.body.insertBefore(d, document.body.firstChild);
  d.style.display='block';
  d.style.height=document.body.scrollHeight;
 }
</script>

 

function getPageXY() {
 var xScroll, yScroll;
 if (window.innerHeight && window.scrollMaxY) {
  xScroll = document.body.scrollWidth;
  yScroll = window.innerHeight + window.scrollMaxY;
 }else if (document.body.scrollHeight > document.body.offsetHeight){
  xScroll = document.body.scrollWidth;
  yScroll = document.body.scrollHeight;
 }else {
  xScroll = document.body.offsetWidth;
  yScroll = document.body.offsetHeight;
 }
 
 var windowWidth, windowHeight;
 if (self.innerHeight) {
  windowWidth = self.innerWidth;
  windowHeight = self.innerHeight;
 }else if (document.documentElement && document.documentElement.clientHeight) {
  windowWidth = document.documentElement.clientWidth;
  windowHeight = document.documentElement.clientHeight;
 }else if (document.body) {
  windowWidth = document.body.clientWidth;
  windowHeight = document.body.clientHeight;
 }
 
 if(yScroll < windowHeight){
  pageHeight = windowHeight;
 }else {
  pageHeight = yScroll;
 }
 
 if(xScroll < windowWidth){
  pageWidth = windowWidth;
 }else {
  pageWidth = xScroll;
 }
 
 var arrayPageXY = new Array(pageWidth,pageHeight,windowWidth,windowHeight);
 return arrayPageXY;
}