拖拽效果

 1 var odiv = document.getElementById("box");
 2             var disX = 0;
 3             var disY = 0;
 4             odiv.onmousedown = function(ev){
 5                 var ev = ev || window.event;
 6                 disX = ev.clientX -odiv.offsetLeft;
 7                 disY = ev.clientY -odiv.offsetTop;
 8                 document.onmousemove = function(ev){
 9                     var ev = ev || window.event;
10                     odiv.style.left = ev.clientX - disX + 'px';
11                     odiv.style.top = ev.clientY - disY + 'px';
12                 }
13                 document.onmouseup = function(){
14                     document.onmousemove = null;
15                     document.onmouseup = null;
16                 }
17             }