能够根据自定义的菜单数据和select，自动设置联级的下拉菜单，可定义默认值
效果：
参数2是select的id集合(按顺序)：
var sel=["sel1","sel2","sel3","sel4","sel5"]
可设置默认值(按顺序)：
var val=["3 ->", "3_1 ->", "3_1_2"];
源码：
<!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>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>JavaScript 自定义多级联动下拉菜单</title>
<script type="text/javascript">
var $ = function (id) {
return "string" == typeof id ? document.getElementById(id) : id;
};
function addEventHandler(oTarget, sEventType, fnHandler) {
if (oTarget.addEventListener) {
oTarget.addEventListener(sEventType, fnHandler, false);
} else if (oTarget.attachEvent) {
oTarget.attachEvent("on" + sEventType, fnHandler);
} else {
oTarget["on" + sEventType] = fnHandler;
}
};
function Each(arrList, fun){
for (var i = 0, len = arrList.length; i < len; i++) { fun(arrList[i], i); }
};
function GetOption(val, txt) {
var op = document.createElement("OPTION");
op.value = val; op.innerHTML = txt;
return op;
};
var Class = {
create: function() {
return function() {
this.initialize.apply(this, arguments);
}
}
}
Object.extend = function(destination, source) {
for (var property in source) {
destination[property] = source[property];
}
return destination;
}
var CascadeSelect = Class.create();
CascadeSelect.prototype = {
//select集合，菜单对象
initialize: function(arrSelects, arrMenu, options) {
if(arrSelects.length <= 0 || arrMenu.lenght <= 0) return;//菜单对象
var oThis = this;
this.Selects = [];//select集合
this.Menu = arrMenu;//菜单对象
this.SetOptions(options);
this.Default = this.options.Default || [];
this.ShowEmpty = !!this.options.ShowEmpty;
this.EmptyText = this.options.EmptyText.toString();
//设置Selects集合和change事件
Each(arrSelects, function(o, i){
addEventHandler((oThis.Selects[i] = $(o)), "change", function(){ oThis.Set(i); });
});
this.ReSet();
},
//设置默认属性
SetOptions: function(options) {
this.options = {//默认值
Default: [],//默认值(按顺序)
ShowEmpty: false,//是否显示空值(位于第一个)
EmptyText: "请选择"//空值显示文本(ShowEmpty为true时有效)
};
Object.extend(this.options, options || {});
},
//初始化select
ReSet: function() {
this.SetSelect(this.Selects[0], this.Menu, this.Default.shift());
this.Set(0);
},
//全部select设置
Set: function(index) {
var menu = this.Menu
//第一个select不需要处理所以从1开始
for(var i=1, len = this.Selects.length; i < len; i++){
if(menu.length > 0){
//获取菜单
var value = this.Selects[i-1].value;
if(value!=""){
Each(menu, function(o){ if(o.val == value){ menu = o.menu || []; } });
} else { menu = []; }
//设置菜单
if(i > index){ this.SetSelect(this.Selects[i], menu, this.Default.shift()); }
} else {
//没有数据
this.SetSelect(this.Selects[i], [], "");
}
}
//清空默认值
this.Default.length = 0;
},
//select设置
SetSelect: function(oSel, menu, value) {
oSel.options.length = 0; oSel.disabled = false;
if(this.ShowEmpty){ oSel.appendChild(GetOption("", this.EmptyText)); }
if(menu.length <= 0){ oSel.disabled = true; return; }
Each(menu, function(o){
var op = GetOption(o.val, o.txt ? o.txt : o.val); op.selected = (value == op.value);
oSel.appendChild(op);
});
},
//添加菜单
Add: function(menu) {
this.Menu[this.Menu.length] = menu;
this.ReSet();
},
//删除菜单
Delete: function(index) {
if(index < 0 || index >= this.Menu.length) return;
for(var i = index, len = this.Menu.length - 1; i < len; i++){ this.Menu[i] = this.Menu[i + 1]; }
this.Menu.pop()
this.ReSet();
}
};
window.onload=function(){
var menu = [
{'val': '1', 'txt': 'value'},
{'val': '2 ->', 'menu': [
{'val': '2_1'},
{'val': '2_2'}
]},
{'val': '3 ->', 'menu': [
{'val': '3_1 ->', 'menu': [
{'val': '3_1_1'},
{'val': '3_1_2'}
]},
{'val': '3_2'}
]},
{'val': '4 ->', 'menu': [
{'val': '4_1 ->', 'menu': [
{'val': '4_1_1 ->', 'menu': [
{'val': '4_1_1_1'}
]}
]}
]}
];
var sel=["sel1", "sel2", "sel3", "sel4", "sel5"];
var val=["3 ->", "3_1 ->", "3_1_2"];
var cs = new CascadeSelect(sel, menu, { Default: val });
$("btnA").onclick=function(){cs.ShowEmpty=!cs.ShowEmpty;}
$("btnB").onclick=function(){
cs.Add(
{'val': '5 ->', 'menu': [
{'val': '5_1 ->', 'menu': [
{'val': '5_1_1 ->', 'menu': [
{'val': '5_1_1_1 ->', 'menu': [
{'val': '5_1_1_1_1'}
]}
]}
]}
]}
)
}
$("btnC").onclick=function(){
cs.Delete(3)
}
}
</script>
<style type="text/css">
.sel select{ width:100px;}
</style>
</head>
<body>
<div class="sel">
<select id="sel1"></select>
<select id="sel2"></select>
<select id="sel3"></select>
<select id="sel4"></select>
<select id="sel5"></select>
</div>
<br />
<div>
<input id="btnA" type="button" value="显示/不显示空值" />
<input id="btnB" type="button" value="添加菜单" />
<input id="btnC" type="button" value="减少菜单" />
</div>
</body>
</html>
本文转自博客园cloudgamer的博客，原文链接：JavaScript 多级联动select，如需转载请自行联系原博主。