用这锻代码 之前请先下载jquery库

var maskStackCount = 0;

function mask(method){

//这里是你想要进行遮罩的窗口，我这里想要遮罩的是一个iframe窗口，也可以用var winObj=$(window)

var winObj=window.top.$("body").find("iframe[name='dialognormaliframe']");

        if(typeof method == "undefined"){
            method="open";
        }
        if (method == "open") {
            if (maskStackCount <= 0) {
                var mask = $("<div id='window-mask' class='window-mask' style='display:none'></div>").appendTo("body");
                mask.css({
                    width:     winObj.width() + "px",
                    height:     winObj.height() + "px",
                    filter: "alpha(opacity=60)"
                }).show();
                    winObj.on("resize.mask", function(){
                    mask.css({
                        width:     winObj.width() + "px",
                        height:     winObj.height() + "px"
                    });
                });
            }
            maskStackCount++;
        }
        else if(method == "close"){
            maskStackCount--;
            $("#window-mask").remove();
                winObj.off("resize.mask");
        }
}