将DIV显示在屏幕中间

/*设置客户端的高和宽*/
function getClientBounds(){
    var clientWidth;
    var clientHeight;
    
    clientWidth = document.compatMode == "CSS1Compat" ? document.documentElement.clientWidth : document.body.clientWidth;
    clientHeight = document.compatMode == "CSS1Compat" ? document.documentElement.clientHeight :   document.body.clientHeight;
        
    return {width: clientWidth, height: clientHeight};
}

 

/*设置客户端的高和宽*/  
function divcenter(){     
    var divId=document.getElementById('mxh');    
    var rr=new getClientBounds();  
    divId.style.display='block';  
    divId.style.left=(rr.width-divId.clientWidth)/2+document.body.scrollLeft;  
    divId.style.top=(rr.height-divId.clientHeight)/2+document.body.scrollTop;     
}