js+html实现遮罩层效果

//遮罩 
 function coverDiv(){ 
 var procbg = document.createElement("div"); //首先创建一个div 
 procbg.setAttribute("id","mybg"); //定义该div的id 
 procbg.style.background = "#000000"; 
 procbg.style.width = "100%"; 
 procbg.style.height = "100%"; 
 procbg.style.position = "fixed"; 
 procbg.style.top = "0"; 
 procbg.style.left = "0"; 
 procbg.style.zIndex = "500"; 
 procbg.style.opacity = "0.6"; 
 procbg.style.filter = "Alpha(opacity=70)"; 
 document.body.appendChild(procbg); 
 } 
 //取消遮罩 
 function hide() { 
 /* document.getElementById('light').style.display="none"; */ 
 $("div[class='xucun_content']").hide(); 
 var body = document.getElementsByTagName("body"); 
 var mybg = document.getElementById("mybg"); 
 body[0].removeChild(mybg); 
 }