基本上MSN、MicroSoft Live 和GOOGLE个性主页 元素可拖动并放置的的实现原理就是对DOM的操作再加上JAVASCRIPT拖动元素。实现起来实际上并不难，但是要做到很美观并符合用户习惯就需要一些时间思考了。
以下代码实现了上述功能，虽然很简单，但是基本上说明了原理。实现更高级的功能当然还需要改进。
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<html>
<head>
<title>DropLayer2</title>
<meta name="GENERATOR" Content="Microsoft Visual Studio .NET 7.1">
<meta name="CODE_LANGUAGE" Content="C#">
<meta name="vs_defaultClientScript" content="JavaScript">
<meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">
<style type="text/css">
div
{
border-right: lightgrey thin solid;
border-top: lightgrey thin solid;
font-weight: bold;
z-index: 2;
text-transform: capitalize;
border-left: lightgrey thin solid;
color: white;
border-bottom: lightgrey thin solid;
background-color: dimgray;
}
</style>
</head>
<body>
<div id="parentDiv" class="parentCss" style="width:100">
<div class="itemCss" onmouseover="InsertDiv(this)">one 1</div>
<div class="itemCss" onmouseover="InsertDiv(this)">two 2</div>
<div class="itemCss" onmouseover="InsertDiv(this)">three 3</div>
<div class="itemCss" onmouseover="InsertDiv(this)">four 4</div>
<div class="itemCss" onmouseover="InsertDiv(this)">five 5</div>
<div class="itemCss" onmouseover="InsertDiv(this)">six 6</div>
<div class="itemCss" onmouseover="InsertDiv(this)">seven 7</div>
<div class="itemCss" onmouseover="InsertDiv(this)">eight 8</div>
<div class="itemCss" onmouseover="InsertDiv(this)">nine 9</div>
<div class="itemCss" onmouseover="InsertDiv(this)">ten 10</div>
</div>
<script language="javascript">
<!--
var obj,obj2; //引发事件对象
var rootNode; //控制对象根节点
var IsDrag=false; //是否抓起
var NullDiv; //空临时层
var x,y; //鼠标与控件的相对坐标
window.onload = Prepare; //窗体加载时委托到Prepare
function Prepare()
{
//生成临时层，并设置其属性
NullDiv = document.createElement("div");
//获得控制对象的根节点元素
rootNode = document.getElementById("parentDiv");
document.onmousemove=MoveIt; //当鼠标在文档上移动时事件委托到MoveIt
document.onmousedown=Drag; //当鼠标按下时事件委托到Drag
document.onmouseup=Release; //当鼠标释放台起时事件委托到Release
}
function Drag()
{
obj = event.srcElement;
x=0;//event.offsetX;
y=0;//event.offsetY;
obj.style.position='absolute';
obj.style.posTop=event.y-y;
obj.style.posLeft=event.x-x;
IsDrag=true;
}
function MoveIt()
{
//window.status = event.x+"|"+event.y+"|"+IsDrag+"|"+x+"|"+y;
if(IsDrag)
{
obj.style.posTop=event.y-y;
obj.style.posLeft=event.x-x;
}
}
function Release()
{
IsDrag=false;
NullDiv.style.display='none';
obj.style.position='';
rootNode.insertBefore(obj,obj2);
}
function InsertDiv(o)
{
if(IsDrag)
{
obj2=o;
NullDiv.style.display='';
NullDiv.style.height='18';
NullDiv.style.width='100';
rootNode.insertBefore(NullDiv,obj2);
}
}
//-->
</script>
</body>
</html>
