$(function() {var docHeight = $(document).height();$("body").append("<div id="overlay"></div>");$("#overlay") .height(docHeight) .css({ "opacity" : 0.4, "position": "absolute", "top": 0, "left": 0, "background-color": "black", "width": "100%", "z-index": 5000 });});希望本文所述对大家的jQuery程序设计有所帮助。