同事在网上的找的下拉列表框出现位置不对的和加载慢的BUG，反正多选下拉列表框实现也很简单，与其看那些结构混乱的代码，不如自己重新实现一个。

先看效果： http://demo.jb51.net/js/2012/jquery_demo/jquery_select.html

JS:
复制代码 代码如下:
(function ($) {
$.fn.extend({
MultDropList: function (options) {
var op = $.extend({ wraperClass: "wraper", width: "150px", height: "200px", data: "", selected: "" }, options);
return this.each(function () {
var $this = $(this); //指向TextBox
var $hf = $(this).next(); //指向隐藏控件存
var conSelector = "#" + $this.attr("id") + ",#" + $hf.attr("id");
var $wraper = $(conSelector).wrapAll("<div><div></div></div>").parent().parent().addClass(op.wraperClass);
var $list = $('<div class="list"></div>').appendTo($wraper);
$list.css({ "width": op.width, "height": op.height });
//控制弹出页面的显示与隐藏
$this.click(function (e) {
$list.toggle();
e.stopPropagation();
});
$(document).click(function () {
$list.hide();
});
$list.filter("*").click(function (e) {
e.stopPropagation();
});
//加载默认数据
$list.append('<ul><li><input type="checkbox" class="selectAll" value="" /><span>全部</span></li></ul>');
var $ul = $list.find("ul");
//加载json数据
var listArr = op.data.split("|");
var jsonData;
for (var i = 0; i < listArr.length; i++) {
jsonData = eval("(" + listArr[i] + ")");
$ul.append('<li><input type="checkbox" value="' + jsonData.k + '" /><span>' + jsonData.v + '</span></li>');
}
//加载勾选项
var seledArr;
if (op.selected.length > 0) {
seledArr = selected.split(",");
}
else {
seledArr = $hf.val().split(",");
}
$.each(seledArr, function (index) {
$("li input[value='" + seledArr[index] + "']", $ul).attr("checked", "checked");
var vArr = new Array();
$("input[class!='selectAll']:checked", $ul).each(function (index) {
vArr[index] = $(this).next().text();
});
$this.val(vArr.join(","));
});
//全部选择或全不选
$("li:first input", $ul).click(function () {
if ($(this).attr("checked")) {
$("li input", $ul).attr("checked", "checked");
}
else {
$("li input", $ul).removeAttr("checked");
}
});
//点击其它复选框时，更新隐藏控件值,文本框的值
$("input", $ul).click(function () {
var kArr = new Array();
var vArr = new Array();
$("input[class!='selectAll']:checked", $ul).each(function (index) {
kArr[index] = $(this).val();
vArr[index] = $(this).next().text();
});
$hf.val(kArr.join(","));
$this.val(vArr.join(","));
});
});
}
});
})(jQuery);
$(document).ready(function () {
$("#txtTest").MultDropList({ data: $("#hfddlList").val() });
});
</script>

CSS:
复制代码 代码如下:
.wraper
{
position: relative;
}
.list
{
width: 200px;
height: 200px;
overflow: auto;
position: absolute;
border: 1px solid #617775;
display: none;
background: none repeat scroll 0 0 #F0F6E4;
float: left;
}
.list ul li
{
padding-left: 10px;
padding-top: 2px;
padding-bottom: 2px;
border-top: 1px solid black;
}
ul
{
list-style:none outside none;
}

HTML:
复制代码 代码如下:
<asp:HiddenField ID="hfddlList" runat="server" Value='{k:1,v:"南京"}|{k:2,v:"上海"}|{k:3,v:"扬州"}|{k:4,v:"苏州"}|{k:5,v:"无锡"}|{k:6,v:"常州"}|{k:7,v:"盐城"}|{k:8,v:"徐州"}|{k:9,v:"泰州"}|{k:10,v:"淮安"}' />
<div class="testContainer">
<br />
<br />
<br />
<br />
<div style="margin-left: 300px; height: 30px;">
<asp:TextBox ID="txtTest" runat="server" Width="150px"></asp:TextBox>
<asp:HiddenField ID="hfTest" runat="server" Value="3,5" />
</div>
</div>