原生JS拖拽

放代码：
给要拖拽的盒子设置：决定定位
 1 <!DOCTYPE html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <meta name="viewport" content="width=device-width, initial-scale=1.0">
 6     <title>Document</title>
 7     <style>
 8         #div1 {
 9              500px;
10             height: 500px;
11             position: absolute;
12             background-color: pink;
13         }
14     </style>
15 </head>
16 <body>
17     <div id="div1"></div>
18     <script>
19         window.onload=function()
20         {
21             var oDiv=document.getElementById('div1');
22             oDiv.onmousedown=function(ev)
23             {
24                 var oEvent=ev||event;
25                 var x=0;
26                 var y=0;
27                 x=oEvent.clientX-oDiv.offsetLeft;
28                 y=oEvent.clientY-oDiv.offsetTop;
29                 document.onmousemove=function(ev)
30                 {
31                     var oEvent=ev||event;
32                     var out1=oEvent.clientX-x;
33                     var out2=oEvent.clientY-y;
34                     
35                     var oWidth=document.documentElement.clientWidth-oDiv.offsetWidth;
36                     var oHeight=document.documentElement.clientHeight-oDiv.offsetHeight;
37 
38                     if(out1<0)
39                     {out1=0;}
40                     else if (out1>oWidth)
41                     {
42                         out1=oWidth;
43                     }
44                     
45                     
46                     if(out2<0)
47                     {out2=0;}
48                     else if (out2>oHeight)
49                     {
50                         out2=oHeight;
51                     }
52                     
53                     oDiv.style.left=out1+'px';
54                     oDiv.style.top=out2+'px';
55                 }
56                     document.onmouseup=function()
57                 {
58                     document.onmousemove=null;
59                     document.onmouseup=null;    
60                 }
61                 return false;//解决firefox低版本的bug问题
62             }
63         }
64     </script>
65 </body>
66 </html>
觉得有一句话非常有道理：学习是一个不断抄袭和重复的过程