行拖動的實現思路非常簡單,選中一行,往上拖就與上面的行交換位置,往下拖就與下面的行交換位置。問題是如何得到交換行。我見過一個非常詳細的教程,它會把表格裡的每一行的高度與Y坐標計算出來,換言之,都時是比較e.pageX是否在[rowTop,rowBottom]區間之內。但這也帶來第二個問題,有多少行就有多個這樣的區間。於是解法就變成取事件源對象,然後再往上取其父對象,如果其父對象是TR元素,就取其[rowTop,rowBottom]區間....思路非常直接,同時也客觀做出一個限制——不能使用代理拖動。先不談是拖動代理還是拖動實物,光是在移動鼠標的過程要做的計算量就非常大,幸好還在IE的承受范圍之內。有更好的方法嗎?
人之所以先入為主,因為他就握著這麼幾把鎖匙。如果他手上的鎖匙非常多時,他在開門時就會稍微停下來,認真挑選了。因此熟悉掌握越多的原生API就越好,我們就才獲取更優的選項。換一個思路,在拖動時(mousedown)保存當前行及其樣式與坐標,拖動中取得鼠標所在位置上的元素,這個元素是使用一個巧妙的API取得document.elementFromPoint(x,y)。通常情況,我們取得的是TD,當然如果你在裡面塞進一個DIV,那就是DIV羅。然後我們再取得其TR元素,然後比較mousedown時保存的TR元素是不是同一個元素,不是同一個元素,我們才做進一步的操作。這時我們就要判其是向上移向下移,簡單的減法而已。接著是交換兩行,使用insertBefore。最後當mouseup時,還原行的樣式就是!由於沒有復雜的坐標計算,整個程式出奇的高效!
完整演示代碼
<!doctype html>
<html>
<head>
<title>表格行拖動</title>
<script>
window.onload = function(){
//綁定事件
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);
}
//精確獲取樣式
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時拖動行
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;//是否向下移動
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)
}
//顯示為可移動的狀態
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>表格行拖動</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>
核心代碼
window.onload = function(){
//綁定事件
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);
}
//精確獲取樣式
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時拖動行
var dragObj = dragManager.dragObj;
if(dragObj){
e = e || event;//清除選區
if(window.getSelection){//w3c
window.getSelection().removeAllRanges();
}else if(document.selection){
document.selection.empty();//IE
}
var y = e.clientY;
var down = y > dragManager.clientY;//是否向下移動
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)
}
//顯示為可移動的狀態
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);
}
實現代碼二
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head >
<title>無標題頁</title>
</head>
<body>
<table id="tb1" border="1" cellpadding="3">
<tr>
<th>移動</th>
<th>數據</th>
<th>數據</th>
<th>數據</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下測試通過哦。