DIV拖动及DOM2移除事件注意事项

记录这个没别的意思，之前这段代码貌似没有问题，但是调试的时候移除事件貌似不能用源代码如下：

<!--拖动div-->
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<style>
*{margin: 0;padding: 0}
.mg10{margin: 10px;}
.g{background: #333333}
.fl{float: left;}
#div11{width:200px;height:400px;}
#div2{width:300px;height:610px;}
#div12{width:200px;height:200px;}
</style>
<!--<script src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.7.2.min.js"></script>-->

</head>
<body>
    
<!-- <div id="div1" class="fl">
    <div id="div11" class="g mg10"></div>
    <div id="div12" class="g mg10"></div>
</div> -->

<div id="div2" class="g mg10"></div>
<script type="text/javascript">
    
  /**
  * 绑定事件
  **/   
  var addEvent =  function(obj, eventName, handle) {

    if(window.addEventListener) {
        obj.addEventListener(eventName, handle, false);
    }else {
        obj.attachEvent("on" + eventName, handle);
    }
  }

  var removeEvent = function (obj, eventName, handle){ 
    if (window.removeEventListener) {
      obj.removeEventListener(eventName, handle, false);
    }else if(window.detachEvent){ 
      obj.detachEvent("on" + eventName, handle);  
    }else {
      obj["on" + eventName] = null;
    }

  }; 

  var $ = function(id) {
    return "string" == typeof id ? document.getElementById(id) : id;
  }

  //js兼容性
  var page = {
    event: function (evt) {
        var ev = evt || window.event;
        return ev;
    },
    target: function(evt) {
        return evt.target || evt.srcElement;
    },
    pageX: function (evt) {
        var e = this.event(evt);
        return e.pageX || (e.clientX + document.body.scrollLeft - document.body.clientLeft);
    },
    pageY: function (evt) {
        var e = this.event(evt);
        return e.pageY || (e.clientY + document.body.scrollTop - document.body.clientTop);
    },
    layerX: function (evt) {
        var e = this.event(evt);
        return e.layerX || e.offsetX;
    },
    layerY: function (evt) {
        var e = this.event(evt);
        return e.layerY || e.offsetY;
    }
  }             

  var drag = function(obj) {
    obj.style.position="absolute";
    addEvent(obj,"mousedown", function(event){
      var target = page.target(event);
      var x = page.layerX(event);
      var y = page.layerY(event); 
     
      addEvent(obj,"mousemove", function(event){
        var tx = page.pageX(event) - x;
        var ty = page.pageY(event) - y;
        target.style.left = tx + "px";
        target.style.top = ty + "px";
      });

      addEvent(obj,"mouseup", function(event){
        obj.style.position="relative";
        removeEvent(obj, "mousemove",function(){});
        
      });
    });
  }

    drag($("div2"));
    
  
</script>



</body>
</html>

一直搞不懂为什么事件不能移除？这个代码就一直放下了，结果刚才看《javascript高级程序设计》才知道removeEventListener不能传无参的构造函数，因为addEventListener可以给元素绑定多个事件，所以removeEventListener的时候找不到了！修改好的代码如下：

 /**
  * 绑定事件
  **/   
  var addEvent =  function(obj, eventName, handle) {

    if(window.addEventListener) {
        obj.addEventListener(eventName, handle, false);
    }else {
        obj.attachEvent("on" + eventName, handle);
    }
  }

  var removeEvent = function (obj, eventName, handle){ 
    if (window.removeEventListener) {
      obj.removeEventListener(eventName, handle, false);
    }else if(window.detachEvent){ 
      obj.detachEvent("on" + eventName, handle);  
    }else {
      obj["on"+eventName] = null;
    }

  }; 

  var $ = function(id) {
    return "string" == typeof id ? document.getElementById(id) : id;
  }

  //js兼容性
  var page = {
    event: function (evt) {
        var ev = evt || window.event;
        return ev;
    },
    target: function(evt) {
        return evt.target || evt.srcElement;
    },
    pageX: function (evt) {
        var e = this.event(evt);
        return e.pageX || (e.clientX + document.body.scrollLeft - document.body.clientLeft);
    },
    pageY: function (evt) {
        var e = this.event(evt);
        return e.pageY || (e.clientY + document.body.scrollTop - document.body.clientTop);
    },
    layerX: function (evt) {
        var e = this.event(evt);
        return e.layerX || e.offsetX;
    },
    layerY: function (evt) {
        var e = this.event(evt);
        return e.layerY || e.offsetY;
    }
  }             

  var drag = function(obj) {
    obj.style.position="absolute";
    var mousedownFun, mousemoveFun, mouseupFun, x, y, target;
    mousedownFun = function(event){
        target = page.target(event);
        x = page.layerX(event);
        y = page.layerY(event); 
       
        addEvent(obj,"mousemove", mousemoveFun);

        addEvent(obj,"mouseup", mouseupFun);
    };

    mousemoveFun = function(event){
        var tx = page.pageX(event) - x;
        var ty = page.pageY(event) - y;
        target.style.left = tx + "px";
        target.style.top = ty + "px";
    };

    mouseupFun = function(event) {
        removeEvent(obj, "mousemove",mousemoveFun);
        removeEvent(obj, "mouseup",mouseupFun);
    }
    addEvent(obj,"mousedown", mousedownFun);
  }

    drag($("div2"));

《javascript高级程序设计》不愧是大师写的书，赞

DIV拖动及DOM2移除事件注意事项

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