本章节分享一段代码实例，它模拟红丝线了map集合的功能。

代码实例:

var Map = function (){
  /************基础变量**************/
  var hashmap = {};
  var keys = [];
  var vals = [];
  var entrys = [];
  var size = 0;
  var index = {};
   
  var Entry = function(key,value){
    var entryKey = key;
    var entryValue = value;
    this.getKey = function (){
      return entryKey;
    };
    this.getValue = function(){
      return entryValue;
    };
  };
  /************基本方法 按字母排序**************/
  this.clear = function(key) {
    hashmap[key] = undefined;
    var i = index[key];
    entrys.splice(i,1);
    vals.splice(i,1);
    keys.splice(i,1);
    size --;
  };
     
  this.entrySet = function() {
    return entrys;
  };
     
  this.get = function(key){
    return hashmap[key];
  };
     
  this.isEmpty = function() {
    if(hashmap) return true;
    return false;
  };
   
  this.keySet = function() {
    return keys;
  };
     
  this.put = function(key,value){
    if(!this.get(key)){
      entrys.push(new Entry(key,value));
      keys.push(key);
      vals.push(value);
      index[key] = size;
      size ++;
    } else {
      var i = index[key];
      entrys[i] = new Entry(key,value);
      vals[i] = value;
    }
    hashmap[key] = value;
  };
   
  this.size = function() {
    return size;
  };
     
  this.values = function() {
    return vals;
  };
};
/************扩展方法**************/
Map.prototype = {
  containsKey : function(key) {
    if(this.get(key)) return true;
    return false;
  },
  putAll : function(set) {
    for(var e in set){
      if(set[e]){
        this.put(e,set[e]);
      }
    }
  },
  remove : function(key) {
    var v = this.get(key);
    this.clear(key);
    return v;
  }
};
var h = new Map();
h.put('a',10);
h.put('b',11);
h.put('c',3);
h.put('d',5);
console.info(h.size());
h.clear('a');
console.info(h.containsKey('a'));
console.info(h.containsKey('b'));
console.info(h.size());
   
console.log(h.entrySet());
console.log(h.keySet());
console.log(h.values());
   
for(var i in h.entrySet()){
  var obj = h.entrySet()[i];
  console.log(obj.getKey() + ":" + obj.getValue());
}