1.面向过程的拖拽实现代码：
<!DOCTYPE html>
<html>
<head>
<title>drag Div</title>
<style type="text/css">
#div1{width: 100px;height: 100px;background: red;position: absolute;}
</style>
<script type="text/javascript">
window.onload=function(){
var oDiv=document.getElementById('div1');
var disX=0;
var disY=0;
oDiv.onmousedown=function(ev){
var oEvent=ev||event;
disX=oEvent.clientX-oDiv.offsetLeft;
disY=oEvent.clientY-oDiv.offsetTop;
document.onmousemove=function(ev){
var oEvent=ev||event;
var l=oEvent.clientX-disX;
var t=oEvent.clientY-disY;
if (l<0)
{l=0;}
else if(l>document.documentElement.clientWidth-oDiv.offsetWidth){
l=document.documentElement.clientWidth-oDiv.offsetWidth;
}
if (t<0)
{t=0;}
else if(t>document.documentElement.clientHeight-oDiv.offsetHeight){
l=document.documentElement.clientHeight-oDiv.offsetHeight;
}
oDiv.style.left=l+'px';
oDiv.style.top=t+'px';
};
document.onmouseup=function(){
document.onmousemove=null;
document.onmouseup=null;
}
};
return false;
};
</script>
</head>
<body>
<div id="div1"></div>
</body>
</html>
2.面向对象的实现方法，只用新建对象，可以实现多个div的拖拽运动
<!DOCTYPE html>
<html>
<head>
<title>drag Div</title>
<style type="text/css">
#div1{width: 100px;height: 100px;background: red;position: absolute;}
#div2{width: 100px;height: 100px;background: yellow;position: absolute;}
</style>
<script type="text/javascript">
window.onload=function(){
new Drag('div1');
new Drag('div2');
}
function Drag(id){
var _this=this;
this.disX=0;
this.dixY=0;
this.oDiv=document.getElementById(id);
this.oDiv.onmousedown=function()
{
_this.fnDown();
};
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(){
_this.fnMove();
};
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){
l=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>
