JavaScript实现Java中Map容器的方法

function Map(){
  var obj = new Object(); //空对象容器,承装键值对
  //put方法
  this.put = function(key,value){
    obj[key] = value;   //把键值对绑定obj对象上
  }
  //size方法,获取Map容器个数
  this.size = function(){
    var count;
    for(var attr in obj){
      count++;
    }
    return count;
  }
  //get方法,根据key取得value
  this.get = function(key){
    if(obj[key] || obj[key] === 0 || obj[key] === false){
      return obj[key];
    }else{
      return null;
    }
  }
  //remove方法,根据key来删除键值对
  this.remove = function(key){
    if(obj[key] || obj[key] === 0 || obj[key] === false){
      delete obj[key];
    }
  }
  //遍历map容器元素方法,eachMap
  this.eachMap = function(fn){
    for(var attr in obj){
      fn(attr,obj[attr]);
    }
  }
}