面向對象--拖拽

 1 function Drag(id){
 2     this.obj = document.getElementById(id);
 3     this.disX = 0;
 4     this.disY = 0;
 5 }
 6 
 7 Drag.prototype.init = function(){
 8     var self = this;
 9     
10     this.obj.onmousedown = function(ev){
11         var event = ev || window.event;
12         self.mouseDown(event);
13     }
14     
15     return false;
16 };
17 
18 Drag.prototype.mouseDown = function(ev){
19     var self = this;
20     this.disX = event.clientX - this.obj.offsetLeft;
21     this.disY = event.clientY - this.obj.offsetTop;
22     
23     document.onmousemove = function(ev){
24         self.mouseMove();
25     }
26     
27     document.onmouseup = function(){
28         self.mouseUp();
29     }
30 };
31 
32 
33 Drag.prototype.mouseMove = function(){
34     this.obj.style.left = (event.clientX - this.disX) + 'px';
35     this.obj.style.top = (event.clientY - this.disY) + 'px';
36 };
37 
38 Drag.prototype.mouseUp = function(){
39     document.onmousemove = null;
40     document.onmouseup = null;
41 }