javascript中伪哈希表的简单实现！

function HashTable(){
      this.add=Carinfo_hashAdd;
      this.del=Carinfo_hashDel;
      this.getValue=Carinfo_hashgetVal;
      this.containsKey=Carinfo_hashifKey;
      this.size=Carinfo_hashgetLength;
      this.hashtable=new Array();
    }        
    //添加
    function Carinfo_hashAdd(key,value){
      if (key != null && value != null){
        if (Carinfo_hashifKey(key) == false){
            this.hashtable[key] = value;
        }
      }
    }
    //删除
    function Carinfo_hashDel(key){
        delete this.hashtable[key];
    }
    //取值
    function Carinfo_hashgetVal(key){ 
        return this.hashtable[key];
    }
    //是否含key
    function Carinfo_hashifKey(key){
      for(var i in this.hashtable){
       if(i==key && this.hashtable[i]!= null)
       return true;    
      }
       return false;
    }
    //求长度
    function Carinfo_hashgetLength(){
       var len=0;
       for(var i in this.hashtable)
       {
          if(this.hashtable[i]!=null)
           len++
        }
       return len;
    }