Javascript implementation of pop up layer background ash simulate of easyui dialog

The page is ugly, only to achieve the function. ^ ^

 
<title> imitation easyui dialog The effect of </title> 
<script> 
//Get page elements
var getElement = function() { 
return document.getElementById(arguments[0]) || false; 
} 
function openDialog(dialogId) { 
var maskId = "mask"; 
//If so, delete the original
if (getElement(dialogId)) { 
document.removeChild(getElement(dialogId));//Delete: div pops up
} 
if (getElement(maskId)) { 
document.removeChild(getElement(maskId));//Delete operation: popup non - operational (mask) layer
} 

//Background grey
var maskDiv = document.createElement("div"); 
maskDiv.id = maskId; 
maskDiv.style.position = "absolute"; 
maskDiv.style.zIndex = "1"; 
maskDiv.style.width = document.body.scrollWidth + "px"; 
maskDiv.style.height = document.body.scrollHeight + "px"; 
maskDiv.style.top = "0px"; 
maskDiv.style.left = "0px"; 
maskDiv.style.background = "gray"; 
maskDiv.style.filter = "alpha(opacity=10)"; 
maskDiv.style.opacity = "0.30";//transparency
document.body.appendChild(maskDiv);//Add a background layer to the body

//Dialog 
var dialogDiv = document.createElement("div"); 
dialogDiv.id = dialogId; 
dialogDiv.style.position = "absolute"; 
dialogDiv.style.zIndex = "9999"; 
dialogDiv.style.width = "400px"; 
dialogDiv.style.height = "200px"; 
dialogDiv.style.top = (parseInt(document.body.scrollHeight) - 200) / 2 + "px"; //Center of the screen
dialogDiv.style.left = (parseInt(document.body.scrollWidth) - 400) / 2 + "px"; //Center of the screen
dialogDiv.style.background = "white"; 
dialogDiv.style.border = "1px solid gray"; 
dialogDiv.style.padding = "5px"; 
dialogDiv.innerHTML = "(Dialog Content)"; 
//Close in Dialog: close the background and Dialog layers
var closeControlloer = document.createElement("a");//Create a hyperlink (as a closing trigger)
closeControlloer.href = "#"; 
closeControlloer.innerHTML = " Shut down "; 
closeControlloer.onclick = function() { 
document.body.removeChild(getElement(dialogId));//Delete diaglog
document.body.removeChild(getElement(maskId));//Delete background layer
} 
dialogDiv.appendChild(closeControlloer);//Add a close operation to dialog
document.body.appendChild(dialogDiv);//Add dialog to the body
} 
</script> 
<a href="#" onclick="openDialog('dialog');">Open Dialog</a> 

< img SRC = "border = 0 / / files.jb51.net/file_images/article/201312/201312271135362.gif? 20131127113551 ">