;(function($){
 $.fn.extend({
 "jLzindex" : function(){ //用于判斷和設置各個對話框的z-index
 var $dragIndex = $(this);
 var arrzIndex = new Array();
 for(var i=0; i < $dragIndex.length; i++){ //初始化數(shù)組元素值，并按拖拽項順序設置z-index值
 var zIdxNum = 10000 - i - i -2;
 arrzIndex[i] = {"getId":"drag" + ($dragIndex.length - i),"zIdx":zIdxNum};
 $("#drag" + ($dragIndex.length - i)).css("z-index",zIdxNum);
 }
 $dragIndex.mousedown(function(){
 var i = 0;
 var dIndex = 0;
 while(arrzIndex[i]){ //找到當前點擊項在數(shù)組里的下標
 if(arrzIndex[i].getId == $(this).attr("id")){ dIndex = i;}
 i++;
 }
 for(var i = dIndex; i >=0; i--){ //把點擊項移至數(shù)組第一位，其他項后移
 if(i > 0){
 arrzIndex[i].getId = arrzIndex[i-1].getId;
 $("#" + arrzIndex[i].getId).css("z-index",arrzIndex[i].zIdx);
 } else{
 arrzIndex[i].getId = $(this).attr("id");
 $("#" + arrzIndex[i].getId).css("z-index",arrzIndex[i].zIdx);
 }
 }
 });
 },
 "jLdraggable" : function(mod){ //拖拽插件
 var model = mod;
 var draggable = false; 
 var $drag = $(this);
 $drag.find(".dragBar").mousedown(function(e){
 draggable = true;
 var mouseLeft = e.pageX - $drag.find(".dragBar").offset().left; //鼠標在拖拽區(qū)域中的橫向距離
 var mouseTop = e.pageY - $drag.find(".dragBar").offset().top; //鼠標在拖拽區(qū)域中的橫向距離
 if(model == "cFade"){ //原位置元素半透明
 $drag.clone(false).appendTo("body").addClass("dragShadow").fadeTo(0,0.2).css("z-index",parseInt($drag.css("z-index")) - 1);
 } else if(model == "dFade"){ //跟隨鼠標元素半透明
 $drag.clone(false).appendTo("body").addClass("dragShadow").css("z-index",parseInt($drag.css("z-index")) - 1);
 $drag.fadeTo(0,0.2);
 }
 $(document).mousemove(function(e){
 if(draggable){
 var winWidth = $(window).width();
 var winHeight = $(window).height();
 var dragLeft = e.pageX - mouseLeft;
 var dragTop = e.pageY - mouseTop;
 
 //拖拽框不能超出窗口邊界
 if(dragLeft < 0){dragLeft = 0;}
 if(dragLeft + $drag.width() > winWidth){
 dragLeft = winWidth - $drag.width();
 }
 if(dragTop < 0){dragTop = 0;}
 if(dragTop + $drag.height() > winHeight){
 dragTop = winHeight - $drag.height();
 }
 
 $drag.css("left",dragLeft + "px");
 $drag.css("top",dragTop + "px");
 } else{
 return false;
 }
 });
 });
 $(document).mouseup(function(){
 draggable = false;
 $(".dragShadow").remove();
 if(model == "dFade"){
 $drag.fadeTo(0,1); 
 }
 });
 }
 })
})(jQuery)

<script type="text/javascript" src="js/jquery.min.js"></script> 
<script type="text/javascript" src="js/jquery.jLdraggable.js"></script> 
<script type="text/javascript">
$(document).ready(function(){
 $("#drag1").jLdraggable(); //無參數(shù)，沒有影子
 $("#drag2").jLdraggable("cFade"); //cFade，定義原位置半透明陰影
 $("#drag3").jLdraggable("dFade"); //dFade，定義跟隨鼠標的半透明陰影
 $(".dragIndex").jLzindex(); //多個窗口的z-index處理
});
</script>
<style type="text/css">

.dragTitle{
 width:120px;
 height:27px;
 background:url(images/drag_01.jpg);
 cursor:move;
}
.dragContent{
 width:120px;
 height:73px;
 background:url(images/drag_02.jpg);
 line-height:73px;
 text-align:center;
}

#drag1{
 width:120px; 
 position:absolute; 
 left:10px; 
 top:10px;
}
#drag2{
 width:120px; 
 position:absolute; 
 left:90px; 
 top:90px;
}
#drag3{
 width:120px; 
 position:absolute; 
 left:170px; 
 top:170px;
}
</style>
<div id="drag1" class="dragIndex">
 <div class="dragBar dragTitle"></div>
 <div class="dragContent">無參數(shù)</div>
</div>
<div id="drag2" class="dragIndex">
 <div class="dragBar dragTitle"></div>
 <div class="dragContent">原位半透明</div>
</div>
<div id="drag3" class="dragIndex">
 <div class="dragBar dragTitle"></div>
 <div class="dragContent">拖拽半透明</div>
</div>