JavaScript实现DIV弹出层及关闭功能

    /******************************
    周旭
    DIV弹出层
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    var cTime;
    function OpenDivLayer(tag)
    {
    
        var divBackground = document.getElementById('divBackground');
        var divShow = document.getElementById('divShow');
        var Position = getPosition();
         
        divBackground.style.display='block';
        divShow.style.display='block';
        
        //背景层
        /*  在火狐这样写不行。
        divBackground.style.width =  document.documentElement.clientWidth;        //层的宽度
    divBackground.style.height = document.documentElement.clientHeight;      //层的高度
    
    divBackground.style.position = "absolute";
    divBackground.style.zIndex = "9998";
        divBackground.style.left = "0";
    divBackground.style.top = "0";
    divBackground.style.right = "0";
    divBackground.style.filter = "alpha(opacity=60)"; //设置背景透明
    divBackground.style.opacity = "0.80"; 
    divBackground.style.color= "#213140";
    divBackground.style.backgroundColor = "#7a7a7a";
    divBackground.style.textAlign = "center";