<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>鼠標(biāo)拖動和拖拽的鼠標(biāo)指針特效</title>
<style>
#box{width:100px;height:100px;background:#966;position:absolute;left:100px;top:100px;cursor:pointer;}
</style>
</head>
<body>
<div id="box"></div>
<script>
var doc=document;
function getViewport(){
  return {width:Math.max(document.documentElement.clientWidth,document.documentElement.scrollWidth),
      height:Math.max(document.documentElement.clientHeight,document.documentElement.scrollHeight)
  };
}
function compareNum(x,minNum,maxNum){
 switch(true){
 case x<minNum:x=minNum;break;
 case x>maxNum:x=maxNum;break;
 default:x;
 }
 return x;
 }

box.style.left='100px'
box.style.top='100px'

box.onmousedown=function(e){
 var e=e||window.event;
 var maxL=getViewport().width-100,
   maxT=getViewport().height-100;
 this.startL=parseInt(this.style.left);
 this.startT=parseInt(this.style.top);
 //alert(e.clientX)
 this.startX=e.clientX;
 this.startY=e.clientY;
 //alert(maxL+':'+maxT+':'+L+':'+T)
 doc.onmousemove=function(e){
 posXY(e,0,0,maxL,maxT);
 };
 doc.onmouseup=function(){
  doc.onmousemove=null;
 doc.onmouseup=null;
 };
 return false;
}
function posXY(e,minL,minT,maxL,maxT){
  var e=e||window.event;
 var x=box.startL-(box.startX-e.clientX);
 var y=box.startT-(box.startY-e.clientY);
 box.style.left=compareNum(x,minL,maxL)+'px'
 box.style.top=compareNum(y,minT,maxT)+'px'
}
</script>
</body>
</html>

[Ctrl+A 全選注:引入外部Js需再刷新一下頁面才能執(zhí)行]

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