<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.οnlοad=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.οnmοusedοwn=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.οnmοusemοve=function(ev){ _this.fnMove(ev); }; document.οnmοuseup=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.οnmοusemοve=null; document.οnmοuseup=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];
}