js拖拽效果的实现

时间：2023-03-09 15:02:35
js拖拽效果的实现

1、最基础的写法

 <!DOCTYPE HTML>

 <html>

 <head>

 <meta charset="utf-8">

 <title>无标题文档</title>

 <style>

 #div1 {width:200px; height:200px; background:yellow; position:absolute;}

 </style>

 <script>

 window.onload=function ()

 {

     var oDiv=document.getElementById('div1');

     oDiv.onmousedown=function (ev)

     {

         var oEvent=ev||event;

         var disX=oEvent.clientX-oDiv.offsetLeft;

         var disY=oEvent.clientY-oDiv.offsetTop;

         document.onmousemove=function (ev)

         {

             var oEvent=ev||event;

             oDiv.style.left=oEvent.clientX-disX+'px';

             oDiv.style.top=oEvent.clientY-disY+'px';

         };

         document.onmouseup=function ()

         {

             document.onmousemove=null;

             document.onmouseup=null;

         };

     };

 };

 </script>

 </head>

 <body>

 <div id="div1"></div>

 </body>

 </html>

2、相比较高级的写法

 <!DOCTYPE HTML>

 <html>

 <head>

 <meta charset="utf-8">

 <title>无标题文档</title>

 <style>

 #div1 {width:200px; height:200px; background:yellow; position:absolute;}

 </style>

 <script>

 var oDiv=null;

 var disX=0;

 var disY=0;

 window.onload=function ()

 {

     oDiv=document.getElementById('div1');

     oDiv.onmousedown=fnDown;

 };

 function fnDown(ev)

 {

     var oEvent=ev||event;

     disX=oEvent.clientX-oDiv.offsetLeft;

     disY=oEvent.clientY-oDiv.offsetTop;

     document.onmousemove=fnMove;

     document.onmouseup=fnUp;

 }

 function fnMove(ev)

 {

     var oEvent=ev||event;

     oDiv.style.left=oEvent.clientX-disX+'px';

     oDiv.style.top=oEvent.clientY-disY+'px';

 }

 function fnUp()

 {

     document.onmousemove=null;

     document.onmouseup=null;

 }

 </script>

 </head>

 <body>

 <div id="div1"></div>

 </body>

 </html>

3、

<!DOCTYPE HTML>

<html>

<head>

<meta charset="utf-8">

<title>无标题文档</title>

<style>

#div1 {width:200px; height:200px; background:yellow; position:absolute;}

#div2 {width:200px; height:200px; background:green; position:absolute;}

</style>

<script src="Drag.js"></script>

<script src="LimitDrag.js"></script>

<script>

window.onload=function ()

{

    new Drag('div1');

    new LimitDrag('div2');

};

</script>

</head>

<body>

<div id="div1">普通拖拽</div>

<div id="div2">限制范围</div>

</body>

</html>

Dray.js

 function Drag(id)

 {

     var _this=this;

     this.disX=0;

     this.disY=0;

     this.oDiv=document.getElementById(id);

     this.oDiv.onmousedown=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.onmousemove=function (ev)

     {

         _this.fnMove(ev);

     };

     document.onmouseup=function ()

     {

         _this.fnUp();

     };

 };

 Drag.prototype.fnMove=function (ev)

 {

     var oEvent=ev||event;

     this.oDiv.style.left=oEvent.clientX-this.disX+'px';

     this.oDiv.style.top=oEvent.clientY-this.disY+'px';

 };

 Drag.prototype.fnUp=function ()

 {

     document.onmousemove=null;

     document.onmouseup=null;

 };

LimitDrag.js

 function LimitDrag(id)

 {

     Drag.call(this, id);    //继承属性

 }

 for(var i in Drag.prototype)

 {

     LimitDrag.prototype[i]=Drag.prototype[i];

 }

 LimitDrag.prototype.fnMove=function (ev)

 {

     var oEvent=ev||event;

     var l=oEvent.clientX-this.disX;

     var t=oEvent.clientY-this.disY;

     if(l<)

     {

         l=0;

     }

     else if(l>document.documentElement.clientWidth-this.oDiv.offsetWidth)

     {

         l=document.documentElement.clientWidth-this.oDiv.offsetWidth;

     }

     this.oDiv.style.left=l+'px';

     this.oDiv.style.top=t+'px';

 };

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