jquery移动listbox的值原理及代码

<div style="width:240px;">
<div style="width:100px;float:left;">
<select size="4" name="listLeft" id="listLeft" class="normal">
</select>
</div>
<div style="width:40px;float:left; padding-top:20px;">
<input type="button" id="btnRight" value=">>" /><br />
<input type="button" id="btnLeft" value="<<" />
</div>
<div style="width:100px;float:left;">
<select size="4" name="listRight" id="listRight" class="normal">
</select>
</div>
</div>

//data
var vData = { "datalist":
[
{ "data": "jQuery", "text": "jQuery" },
{ "data": "Asp.net", "text": "Asp.net" },
{ "data": "internet", "text": "internet" },
{ "data": "Sql", "text": "Sql" }
]
};

//bind data
var vlist = "";
//遍历json数据
jQuery.each(vData.datalist, function(i, n) {
vlist += "<option value=" + n.data + ">" + n.text + "</option>";
});
//绑定数据到listLeft
$("#listLeft").append(vlist);
//left move
$("#btnRight").click(function() {
//数据option选中的数据集合赋值给变量vSelect
var vSelect = $("#listLeft option:selected");
//克隆数据添加到listRight中
vSelect.clone().appendTo("#listRight");
//同时移除listRight中的option
vSelect.remove();
});
//right move
$("#btnLeft").click(function() {
var vSelect = $("#listRight option:selected");
vSelect.clone().appendTo("#listLeft");
vSelect.remove();
});