javascript 拖动表格行实现代码

行拖动的实现思路非常简单，选中一行，往上拖就与上面的行交换位置，往下拖就与下面的行交换位置。问题是如何得到交换行。我见过一个非常详细的教程，它会把表格里的每一行的高度与Y坐标计算出来，换言之，都时是比较e.pageX是否在[rowTop,rowBottom]区间之内。但这也带来第二个问题，有多少行就有多个这样的区间。于是解法就变成取事件源对象，然后再往上取其父对象，如果其父对象是TR元素，就取其[rowTop,rowBottom]区间....思路非常直接，同时也客观做出一个限制——不能使用代理拖动。先不谈是拖动代理还是拖动实物，光是在移动鼠标的过程要做的计算量就非常大，幸好还在IE的承受范围之内。有更好的方法吗？

人之所以先入为主，因为他就握着这么几把锁匙。如果他手上的锁匙非常多时，他在开门时就会稍微停下来，认真挑选了。因此熟悉掌握越多的原生API就越好，我们就才获取更优的选项。换一个思路，在拖动时（mousedown）保存当前行及其样式与坐标，拖动中取得鼠标所在位置上的元素，这个元素是使用一个巧妙的API取得document.elementFromPoint(x,y)。通常情况，我们取得的是TD，当然如果你在里面塞进一个DIV，那就是DIV罗。然后我们再取得其TR元素，然后比较mousedown时保存的TR元素是不是同一个元素，不是同一个元素，我们才做进一步的操作。这时我们就要判其是向上移向下移，简单的减法而已。接着是交换两行，使用insertBefore。最后当mouseup时，还原行的样式就是！由于没有复杂的坐标计算，整个程式出奇的高效！

完整演示代码

<!doctype html>
<html>
 <head>
  <title>表格行拖动</title>
  <script>
     window.onload = function(){
    //绑定事件
    var addEvent = document.addEventListener ? function(el,type,callback){
     el.addEventListener( type, callback, !1 );
    } : function(el,type,callback){
     el.attachEvent( "on" + type, callback );
    }
    //移除事件
    var removeEvent = document.removeEventListener ? function(el,type,callback){
     el.removeEventListener( type, callback );
    } : function(el,type,callback){
     el.detachEvent( "on" + type, callback);
    }
    //精确获取样式
    var getStyle = document.defaultView ? function(el,style){
     return document.defaultView.getComputedStyle(el, null).getPropertyValue(style)
    } : function(el,style){
     style = style.replace(/\-(\w)/g, function($, $1){
      return $1.toUpperCase();
     });
     return el.currentStyle[style];
    }
    var dragManager = {
     clientY:0,
     draging:function(e){//mousemove时拖动行
      var dragObj = dragManager.dragObj;
      if(dragObj){
       e = e || event;
       if(window.getSelection){//w3c
        window.getSelection().removeAllRanges();
       }else if(document.selection){
        document.selection.empty();//IE
       }
       var y = e.clientY;
       var down = y > dragManager.clientY;//是否向下移动
       var tr = document.elementFromPoint(e.clientX,e.clientY);
       if(tr && tr.nodeName == "TD"){
        tr = tr.parentNode
        dragManager.clientY = y;
        if( dragObj !== tr){
         tr.parentNode.insertBefore(dragObj, (down ? tr.nextSibling : tr));
        }
       };
      }
     },
     dragStart:function(e){
      e = e || event;
      var target = e.target || e.srcElement;
      if(target.nodeName === "TD"){
       target = target.parentNode;
       dragManager.dragObj = target;
       if(!target.getAttribute("data-background")){
        var background = getStyle(target,"background-color");
        target.setAttribute("data-background",background)
       }
       //显示为可移动的状态
       target.style.backgroundColor = "#ccc";
       target.style.cursor = "move";
       dragManager.clientY = e.clientY;
       addEvent(document,"mousemove",dragManager.draging);
       addEvent(document,"mouseup",dragManager.dragEnd);
      }
     },
     dragEnd:function(e){
      var dragObj = dragManager.dragObj
      if (dragObj) {
       e = e || event;
       var target = e.target || e.srcElement;
       if(target.nodeName === "TD"){
        target = target.parentNode;
        dragObj.style.backgroundColor = dragObj.getAttribute("data-background");
        dragObj.style.cursor = "default";
        dragManager.dragObj = null;
        removeEvent(document,"mousemove",dragManager.draging);
        removeEvent(document,"mouseup",dragManager.dragEnd);
       }
      }
     },
     main:function(el){
      addEvent(el,"mousedown",dragManager.dragStart);
     }
    }
    var el = document.getElementById("table");
    dragManager.main(el);
   }

  </script>
  <style>
   .table{
    width:60%;
    border: 1px solid red;
    border-collapse: collapse;
   }
   .table td{
    border: 1px solid red;
    height: 20px;
   }
  </style>
 </head>
 <body>
  <h1>表格行拖动</h1>
  <table id="table" class="table">
   <tbody>
    <tr>
     <td>1</td>
     <td>One</td>
     <td>dom.require</td>
    </tr>
    <tr id="2" >
     <td class="2">2</td>
     <td>Two</td>
     <td>ControlJS </td>
    </tr>
    <tr id="3" >
     <td class="3">3</td>
     <td>Three</td>
     <td>HeadJS</td>
    </tr>
    <tr id="4" >
     <td class="4">4</td>
     <td>Four</td>
     <td>LAB.js</td>
    </tr>
    <tr id="5" >
     <td class="5">5</td>
     <td>Five</td>
     <td>$script.js</td>
    </tr>
    <tr id="6" >
     <td class="6">6</td>
     <td>Six</td>
     <td>NBL.js</td>
    </tr>
   </tbody>
  </table>
 </body>
</html>

核心代码

 window.onload = function(){
 //绑定事件
 var addEvent = document.addEventListener ? function(el,type,callback){
  el.addEventListener( type, callback, !1 );
 } : function(el,type,callback){
  el.attachEvent( "on" + type, callback );
 }
 //移除事件
 var removeEvent = document.removeEventListener ? function(el,type,callback){
  el.removeEventListener( type, callback );
 } : function(el,type,callback){
  el.detachEvent( "on" + type, callback);
 }
 //精确获取样式
 var getStyle = document.defaultView ? function(el,style){
  return document.defaultView.getComputedStyle(el, null).getPropertyValue(style)
 } : function(el,style){
  style = style.replace(/\-(\w)/g, function($, $1){
   return $1.toUpperCase();
  });
  return el.currentStyle[style];
 }
 var dragManager = {
  clientY:0,
  draging:function(e){//mousemove时拖动行
   var dragObj = dragManager.dragObj;
   if(dragObj){
    e = e || event;//清除选区
    if(window.getSelection){//w3c
     window.getSelection().removeAllRanges();
    }else if(document.selection){
     document.selection.empty();//IE
    }
    var y = e.clientY;
    var down = y > dragManager.clientY;//是否向下移动
    var tr = document.elementFromPoint(e.clientX,e.clientY);
    if(tr && tr.nodeName == "TD"){
     tr = tr.parentNode
     dragManager.clientY = y;
     if( dragObj !== tr){
      tr.parentNode.insertBefore(dragObj, (down ? tr.nextSibling : tr));
     }
    };
   }
  },
  dragStart:function(e){
   e = e || event;
   var target = e.target || e.srcElement;
   if(target.nodeName === "TD"){
    target = target.parentNode;
    dragManager.dragObj = target;
    if(!target.getAttribute("data-background")){
     var background = getStyle(target,"background-color");
     target.setAttribute("data-background",background)
    }
    //显示为可移动的状态
    target.style.backgroundColor = "#ccc";
    target.style.cursor = "move";
    dragManager.clientY = e.clientY;
    addEvent(document,"mousemove",dragManager.draging);
    addEvent(document,"mouseup",dragManager.dragEnd);
   }
  },
  dragEnd:function(e){
   var dragObj = dragManager.dragObj
   if (dragObj) {
    e = e || event;
    var target = e.target || e.srcElement;
    if(target.nodeName === "TD"){
     target = target.parentNode;
     dragObj.style.backgroundColor = dragObj.getAttribute("data-background");
     dragObj.style.cursor = "default";
     dragManager.dragObj = null;
     removeEvent(document,"mousemove",dragManager.draging);
     removeEvent(document,"mouseup",dragManager.dragEnd);
    }
   }
  },
  main:function(el){
   addEvent(el,"mousedown",dragManager.dragStart);
  }
 }
 var el = document.getElementById("table");
 dragManager.main(el);
}

实现代码二

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head >
<title>无标题页</title>
</head>
<body>
<table id="tb1" border="1" cellpadding="3">
<tr>
<th>移动</th>
<th>数据</th>
<th>数据</th>
<th>数据</th>
</tr>
<tr>
<td>*</td>
<td>11111111111</td>
<td>sdgergserhserhserh</td>
<td>awegaw</td>
</tr>
<tr>
<td>*</td>
<td>222222222</td>
<td>serherwwwwww</td>
<td>fafafff</td>
</tr>
<tr>
<td>*</td>
<td>333333333</td>
<td>qqqqqqqwewer</td>
<td>yukyuk</td>
</tr>
</table>
<script type="text/javascript">
var curTr = null;
var tb1 = document.getElementById('tb1');
var trs = tb1.getElementsByTagName('tr');
tb1.onselectstart = function(){
if(curTr){
document.selection.empty(); return true;
}
};
for(var i=1; i<trs.length; i++) {
var tds = trs[i].getElementsByTagName('td');
tds[0].style.cursor = 'move';
tds[0].onmousedown = function(){
curTr = this.parentNode;
curTr.style.backgroundColor = '#eff';
};
tds[0].onmouseover = function() {
if(curTr && curTr != this.parentNode) {
this.parentNode.swapNode(curTr);
}
}
}
document.body.onmouseup = function(){
if(curTr){
curTr.style.backgroundColor = '';
curTr = null;
}
};
</script>
</body>
</html>

注：不兼容firefox，在IE和chrome下测试通过哦。