javascript级联插件

(function(){
	/** 获取对象 */
	var $ = function(id){
		return typeof id == "string" ? document.getElementById(id):id;
	};
	/** 绑定事件流 */
	var bind = function(obj, eventName, funcionName){
		if(obj.addEventListener){
			obj.addEventListener(eventName, funcionName,false);
		 }else if(obj.attachEvent) {
			obj.attachEvent("on" + eventName, funcionName);
		 }else{
			obj["on" + eventName] = funcionName;
		 }
	};
	var Cascading = function(ids){
		/** 存放级联id,数据类型为数组(字符串或者select对象),前一个为后一个的父节点 */
		for(var i=0,len=ids.length;i<len;i++){
			var select = $(ids[i]);
			Array.prototype.push.call(this, select);
			/** 设置初始下标为0 */
			this.indexes.push(0);
			/** 追加事件 */
			bind(select, "change", this._change(select, i));
		}
	};
	Cascading.prototype = {
		/** 级联深度 */
		length:0,
		/** 级联选择下标 */
		indexes:[],
		/** 默认--- 请选择 ---为首项占位符 */
		_defaultSpace:"--- \u8bf7\u9009\u62e9 ---",
		/** 级联数据存放 */
		_buffer:null,
		_opt:function(name, code){
			return new Option(name, code);
		},
		_change:function(select, index){
			/** 延长自身作用域 */
			var tmp = this;
			return function(){
				tmp.indexes[index] = select.selectedIndex;
				/** 超过级联深度 */
				if(index>=tmp.length-1) return;
				var data = tmp._buffer;
				/** 查找需要刷入的数据 */
				for(var i=0;i<=index;i++){
					var idx = tmp.indexes[i];
					/** 去除请选择的级联 */
					if(idx==0) {
						data = null;//清除
						break;
					}
					data = data[idx-1].children;
					if(!data) break;
				}
				/** 刷新下一个级联 */
				tmp._flush(index+1, data);
				/** 清除后续级联值 */
				tmp._reset(index+2);
			}
		},
		setData:function(jsonArray){
			/**
			 * 数据格式为jsonArray,支持多级级联,以省市县为例,
			 * 示例:[
			 *		{"code":"01","name":"北京","children":[{"code":"0001","name":"北京市","children":[{"code":"0000001","name":"朝阳"},{"code":"0000002","name":"海淀"},{"code":"0000003","name":"西城"}]}]},
			 *      {"code":"02","name":"四川","children":[{"code":"0002","name":"成都市","children":[{"code":"0002001","name":"金牛"},{"code":"0002002","name":"成华"},{"code":"0002003","name":"青阳"}]},
			 *       {"code":"0003","name":"乐山市","children":[{"code":"0003001","name":"市中区"},{"code":"0003002","name":"五通桥"},{"code":"0003003","name":"测试区"}]}]}
			 *      ]
			*/
			this._buffer = jsonArray;
			return this;
		},
		_setRoot:function(){
			/** 最大父节点的初始化 */
			var root = this[0];
			/** 填充数据 */
			this._fillData(root, this._buffer);
		},
		_fillData:function(select, data){
			/** 填充级联数据 */
			var opts = select.options;
			/** 设置占位选项 */
			opts[0] = this._opt(this._defaultSpace, "-1");
			opts[0].selected = true;
			/** 无值则不填充相应数据 */
			if(!data) return;
			for(var i=0,len=data.length;i<len;i++){
				opts[opts.length] = this._opt(data[i].name, data[i].code);
			}
		},
		_flush:function(index, data){
			var s = this[index];
			/** 清除原有数据 */
			s.innerHTML = "";
			this._fillData(s, data);
		},
		_reset:function(index){
			/** 重置后续级联数据 */
			for(;index<this.length;index++){
				this[index].innerHTML = "";
				var opts = this[index].options;
				opts[0] = this._opt(this._defaultSpace, "-1");
			}
		},
		setSpace:function(space){
			this._defaultSpace = space;
			return this;
		},
		init:function(){
			/** 初始化根节点 */
			this._setRoot();
			/** 重置后续节点 */
			this._reset(1);
		}
	};
	/** 暴露调用 */
	window.CCD = function(ids){
		if ( ids && ids instanceof Array && ids.length>=2 ){
			return new Cascading(ids);
		}	
	};
})()