javascript实现拖拽并替换网页块元素

找了一些现成的插件，发现都不太符合我的需求，于是参考网上的例子自己实现了一个，还没有优化。

还是贴代码吧：
dragtoreplace

<!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> 
<title>DragToReplaceDeom</title> 
<style> 
#displayRoom{background:#eee;position:relative;float:left;clear:both;padding:30px 0px 0px 20px;margin-left:20px;margin-top:10px;} 
.row{display:inline-block;float:left;width:90px;clear:none;top:0;/**//*background:#DFEFFC;*/} 
.row span{display:inline-block;width:60px;clear:none;background:#9192B1;height:30px;line-height:30px;margin-bottom:30px;text-align:center;} 
span.usr{cursor:pointer;position:absolute;display:inline-block;width:60px;clear:none;height:30px;line-height:30px;margin-bottom:30px;text-align:center;background:#4DA74D;color:#fff;} 
span.usr.catch{background:#BD9B33!important;} 
</style> 
</head> 
<body> 
<div id="displayRoom"> 
<div class="row"> 
<span><span class="usr" id="345">学生甲</span></span><span></span><span></span><span></span></div> 
<div class="row"> 
<span><span class="usr" id="123">学生乙</span></span><span id="3"></span><span></span><span></span></div> 
<div class="row"> 
<span></span><span></span><span></span><span></span> 
</div> 
<div class="row"> 
<span></span><span><span class="usr" id="456">学生一</span></span><span></span><span></span> 
</div> 
</div> 
<script type="text/javascript">var curTarget = null; //鼠标拖拽的目标元素 
var curPos = null; 
var dropTarget = null; //要放下的目标元素 
var iMouseDown = false; //鼠标是否按下 
var lMouseState = false; //前一个iMouseDown状态 
var dragreplaceCont = []; 
var mouseOffset = null; 
var callbackFunc = null; 
Number.prototype.NaN0 = function() { return isNaN(this) ? 0 : this; } 
function setdragreplace(obj, callback) { 
dragreplaceCont.push(obj); 
obj.setAttribute('candrag', '1'); 
if (callback != null && typeof (callback) == 'function') { 
callbackFunc = callback; 
} 
} 
//鼠标移动 
function mouseMove(ev) { 
ev = ev || window.event; 
var target = ev.target || ev.srcElement; 
var mousePos = mouseCoords(ev); 
//如果当前元素可拖拽 
var dragObj = target.getAttribute('candrag'); 
if (dragObj != null) { 
if (iMouseDown && !lMouseState) { 
//刚开始拖拽 
curTarget = target; 
curPos = getPosition(target); 
mouseOffset = getMouseOffset(target, ev); 
// 清空辅助层 
for (var i = 0; i < dragHelper.childNodes.length; i++) dragHelper.removeChild(dragHelper.childNodes[i]); 
//克隆元素到辅助层，并移动到鼠标位置 
dragHelper.appendChild(curTarget.cloneNode(true)); 
dragHelper.style.display = 'block'; 
dragHelper.firstChild.removeAttribute('candrag'); 
//记录拖拽元素的位置信息 
curTarget.setAttribute('startWidth', parseInt(curTarget.offsetWidth)); 
curTarget.setAttribute('startHeight', parseInt(curTarget.offsetHeight)); 
curTarget.style.display = 'none'; 
//记录每个可接纳元素的位置信息，这里一次记录以后多次调用，获取更高性能 
for (var i = 0; i < dragreplaceCont.length; i++) { 
with (dragreplaceCont[i]) { 
if (dragreplaceCont[i] == curTarget) 
continue; 
var pos = getPosition(dragreplaceCont[i]); 
setAttribute('startWidth', parseInt(offsetWidth)); 
setAttribute('startHeight', parseInt(offsetHeight)); 
setAttribute('startLeft', pos.x); 
setAttribute('startTop', pos.y); 
} 
} //记录end 
} //刚开始拖拽end 
} 
//正在拖拽 
if (curTarget != null) { 
// move our helper div to wherever the mouse is (adjusted by mouseOffset) 
dragHelper.style.top = mousePos.y - mouseOffset.y + "px"; 
dragHelper.style.left = mousePos.x - mouseOffset.x + "px"; 
//拖拽元素的中点 
var xPos = mousePos.x - mouseOffset.x + (parseInt(curTarget.getAttribute('startWidth')) / 2); 
var yPos = mousePos.y - mouseOffset.y + (parseInt(curTarget.getAttribute('startHeight')) / 2); 
var havedrop = false; 
for (var i = 0; i < dragreplaceCont.length; i++) { 
with (dragreplaceCont[i]) { 
if (dragreplaceCont[i] == curTarget) 
continue; 
if ((parseInt(getAttribute('startLeft')) < xPos) && 
(parseInt(getAttribute('startTop')) < yPos) && 
((parseInt(getAttribute('startLeft')) + parseInt(getAttribute('startWidth'))) > xPos) && 
((parseInt(getAttribute('startTop')) + parseInt(getAttribute('startHeight'))) > yPos)) { 
havedrop = true; 
dropTarget = dragreplaceCont[i]; 
dropTarget.className = 'usr catch'; 
break; 
} 
} 
} 
if (!havedrop && dropTarget != null) { 
dropTarget.className = 'usr'; 
dropTarget = null; 
} 
} //正在拖拽end 
lMouseState = iMouseDown; 
if (curTarget) return false; //阻止其它响应（如：鼠标框选文本） 
} 
//鼠标松开 
function mouseUp(ev) { 
if (curTarget) { 
dragHelper.style.display = 'none'; //隐藏辅助层 
if (curTarget.style.display == 'none' && dropTarget != null) { 
//有元素接纳，两者互换 
var destP = dropTarget.parentNode; 
var sourceP = curTarget.parentNode; 
destP.appendChild(curTarget); 
sourceP.appendChild(dropTarget); 
dropTarget.className = 'usr'; 
dropTarget = null; 
if (callbackFunc != null) { 
callbackFunc(curTarget); 
} 
} 
curTarget.style.display = ''; 
curTarget.style.visibility = 'visible'; 
curTarget.setAttribute('candrag', '1'); 
} 
curTarget = null; 
iMouseDown = false; 
} 
//鼠标按下 
function mouseDown(ev) { 
//记录变量状态 
iMouseDown = true; 
//获取事件属性 
ev = ev || window.event; 
var target = ev.target || ev.srcElement; 
if (target.onmousedown || target.getAttribute('candrag')) {//阻止其它响应（如：鼠标双击文本） 
return false; 
} 
} 
//返回当前item相对页面左上角的坐标 
function getPosition(e) { 
var left = 0; 
var top = 0; 
while (e.offsetParent) { 
left += e.offsetLeft + (e.currentStyle ? (parseInt(e.currentStyle.borderLeftWidth)).NaN0() : 0); 
top += e.offsetTop + (e.currentStyle ? (parseInt(e.currentStyle.borderTopWidth)).NaN0() : 0); 
e = e.offsetParent; 
} 
left += e.offsetLeft + (e.currentStyle ? (parseInt(e.currentStyle.borderLeftWidth)).NaN0() : 0); 
top += e.offsetTop + (e.currentStyle ? (parseInt(e.currentStyle.borderTopWidth)).NaN0() : 0); 
return { x: left, y: top }; 
} 
//返回鼠标相对页面左上角的坐标 
function mouseCoords(ev) { 
if (ev.pageX || ev.pageY) { 
return { x: ev.pageX, y: ev.pageY }; 
} 
return { 
x: ev.clientX + document.body.scrollLeft - document.body.clientLeft, 
y: ev.clientY + document.body.scrollTop - document.body.clientTop 
}; 
} 
//鼠标位置相对于item的偏移量 
function getMouseOffset(target, ev) { 
ev = ev || window.event; 
var docPos = getPosition(target); 
var mousePos = mouseCoords(ev); 
return { x: mousePos.x - docPos.x, y: mousePos.y - docPos.y }; 
} 
window.onload = function() { 
document.onmousemove = mouseMove; 
document.onmousedown = mouseDown; 
document.onmouseup = mouseUp; 
//辅助层用来显示拖拽 
dragHelper = document.createElement('DIV'); 
dragHelper.style.cssText = 'position:absolute;display:none;'; 
document.body.appendChild(dragHelper); 
setdragreplace(document.getElementById('345')); 
setdragreplace(document.getElementById('123')); 
setdragreplace(document.getElementById('456')); 
}; 
</ script> 
</body> 
</html>

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]

javascript实现拖拽并替换网页块元素_javascript技巧