实现带背景遮罩的弹窗

.blackoverlay
{
    position: absolute;
    background: #666;
    overflow: hidden;
    top: 0px;
    left: 0px;
}

.whitecontent
{
    position: absolute;
    z-index: 1002;
    background: White;
    display: none;
}

function popwindow(obj) {
    var bw = $("body").width();
    var bh = $("body").height();
     
     /*IE*/
    var ww=document.documentElement.clientWidth;
    var wh=document.documentElement.clientHeight;

     /*Chrome*/
    var ww=window.innerWidth;
    var wh=window.innerHeight;

    var cw = $("#"+obj).width();
    var ch = $("#"+obj).height();
    var left = (Math.abs(ww - cw) / 2);
    var top = (Math.abs(wh - ch) / 2);
    $(".blackoverlay").css("width", bw).css("height", bh).show();
    $("#"+obj).css("top", top).css("left", left).show();
}

$(window).resize(function(){
     if($(".whitecontent").is(":visible")){
            popwindow(".whitecontent:visible");
         }
});

function closepop() {
    $(".blackoverlay").css("display", "none");
    $(".whitecontent:visible").css("display", "none");
}