SO fiddle

Test Fiddle mainly for SO Questions

by Nick Craver

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/overcast/jquery-ui.css">
<div id="myItem" style="width: 100px; height: 100px; border: solid 1px #ddd;">Test</div>

CSS

#myItem{
position: absolute;
left: 50%;
margin-left: -350px;
}

JavaScript

var offset = $("#myItem").offset();
alert("Left: " + offset.left + ", Top: " + offset.top);