<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<style>
#div1 {width:100px; height:100px; background:red; position:absolute;}
#div2 {width:100px; height:100px; background:yellow; position:absolute;}
</style>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<script>
window.onload=function(){
new Drag("div1");
new Drag("div2");
}
function Drag(id)
{
var _this=this;
this.oDiv=document.getElementById(id);
this.disX=0;
this.disY=0;
this.oDiv.onmousedown=function(ev){
_this.fnDown(ev);
return false;
};
}
Drag.prototype.fnDown=function(ev)
{
var _this=this;
var oEvent=ev||event;
this.disX=oEvent.clientX-this.oDiv.offsetLeft;
this.disY=oEvent.clientY-this.oDiv.offsetTop;
document.onmousemove=function(ev){
_this.fnMove(ev);
};
document.onmouseup=function(){
_this.fnUp();
};
};
Drag.prototype.fnMove=function(ev)
{
var oEvent=ev||event;
var l=oEvent.clientX-this.disX;
var t=oEvent.clientY-this.disY;
if(l<0)
{
l=0;
}
else if(l>document.documentElement.clientWidth-this.oDiv.offsetWidth)
{
l=document.documentElement.clientWidth-this.oDiv.offsetWidth;
}
if(t<0)
{
t=0;
}
else if(t>document.documentElement.clientHeight-this.oDiv.offsetHeight)
{
t=document.documentElement.clientHeight-this.oDiv.offsetHeight;
}
this.oDiv.style.left=l+'px';
this.oDiv.style.top=t+'px';
};
Drag.prototype.fnUp=function()
{
document.onmousemove=null;
document.onmouseup=null;
};
</script>
</head>
<body>
<div id="div1"></div>
<div id="div2"></div>
</body>
</html>
继承
function LimitDrag(id){
Drag.call(this,id); //继承属性
}
for(var i in Drag.prototype){
LimitDrag.prototype[i]=Drag.prototype[i];
}