function Map() {
/** 存放键的数组(遍历用到) */
this.keys = new Array();
/** 存放数据 */
this.data = new Object();
/**
* 放入一个键值对
* @param {String} key
* @param {Object} value
*/
this.put = function(key, value) {
if(this.data[key] == null){
this.keys.push(key);
}
this.data[key] = value;
};
/**
* 获取某键对应的值
* @param {String} key
* @return {Object} value
*/
this.get = function(key) {
return this.data[key];
};
/**
* 删除一个键值对
* @param {String} key
*/
this.remove = function(key) {
this.keys.remove(key);
this.data[key] = null;
};
/**
* 遍历Map,执行处理函数
*
* @param {Function} 回调函数 function(key,value,index){..}
*/
this.each = function(fn){
if(typeof fn != 'function'){
return;
}
var len = this.keys.length;
for(var i=0;i<len;i++){
var k = this.keys[i];
fn(k,this.data[k],i);
}
};
/**
* 获取键值数组(类似Java的entrySet())
* @return 键值对象{key,value}的数组
*/
this.entrys = function() {
var len = this.keys.length;
var entrys = new Array(len);
for (var i = 0; i < len; i++) {
entrys[i] = {
key : this.keys[i],
value : this.data[i]
};
}
return entrys;
};
/**
* 判断Map是否为空
*/
this.isEmpty = function() {
return this.keys.length == 0;
};
/**
* 获取键值对数量
*/
this.size = function(){
return this.keys.length;
};
/**
* 重写toString
*/
this.toString = function(){
var s = "{";
for(var i=0;i<this.keys.length;i++,s+=','){
var k = this.keys[i];
s += k+"="+this.data[k];
}
s+="}";
return s;
};
}
这里举例简单的 map.each（）方法 求和计算
var map = new Map();
map.put("a",5);
map.put("b",10);
map.put("c",15);
map.put("d",20);
var sum = 0;
if(map.size()>0){
map.each(function(e_key, e_value, e_i){
sum = sum + e_value;
});
}
原文地址：http://blog.51cto.com/xiaok007/2146172