javascript

JS implementation mask layer effect of a simple example

function show(){
    var cover = document.getElementById("cover");
    cover.style.width = document.documentElement.scrollWidth+"px";
    cover.style.height = document.documentElement.scrollHeight+"px";
    cover.style.display = "block";
}
#cover{
    background:gray;
    position:absolute;
    left:0px;
    top:0px;
    display:none;
    z-index:20;
    filter:alpha(opacity=60);
    opacity:0.6 !important;
    }