js实现hashtable的赋值、取值、遍历操作实例详解

HashtableObject.Add(key,value);

HashtableObject.Remove(key);

HashtableObject.Clear();

HashtableObject.Contains(key);

HashTable.prototype = {
    contructor:HashTable,
    //初始化
    initialize:function(){
      this.obj = {};
    },
    //获取hashTable中对象唯一出现的次数
    count:function(){
      var count = 0;
      for(var i in this.content) count++;
      return count;
    },
    //返回hashTable中的值
    items:function(key){
      if(this.contains(key)){
        return this.obj[key];
      }
    },
    //增加值到hashtable
    add:function(key,value){
      if(this.obj.hasOwnProperty(key)){
        return false;
      }else{
        this.obj[key] = value;
        return true;
      }
    },
    //清空hashtable中的值
    clear:function(){
      this.obj = {};
    },
    //检测hashTable对象中是否含有此属性
    contains:function(key){
      return this.obj.hasOwnProperty(key);
    },
    //移除hashTable中对象的值
    remove:function(key){
      delete this.obj[key];
    }
}

// js哈希表
function HashTable() {
  this.ObjArr = {};
  this.Count = 0;
  //添加
  this.Add = function(key, value) {
    if (this.ObjArr.hasOwnProperty(key)) {
      return false; //如果键已经存在，不添加
    }else {
      this.ObjArr[key] = value;
      this.Count++;
      return true;
    }
  }
  //是否包含某项
  this.Contains = function(key) {
    return this.ObjArr.hasOwnProperty(key);
  }
  //取某一项 其实等价于this.ObjArr[key]
  this.GetValue = function(key){
    if (this.Contains(key)) {
      return this.ObjArr[key];
    }else {
      throw Error("Hashtable not cotains the key: " + String(key)); //脚本错误
      //return;
    }
  }
  //移除
  this.Remove = function(key) {
    if (this.Contains(key)) {
      delete this.ObjArr[key];
      this.Count--;
    }
  }
  //清空
  this.Clear = function(){
    this.ObjArr = {}; this.Count = 0;
  }
}
//员工
function employee(id, userName) {
  this.id = id;
  this.userName = userName;
}
function test() {
  var ht = new HashTable();
  var tmpEmployee = null;
  for (var i = 1; i < 6; i++) {
    tmpEmployee = new employee(i, "Employee_" + i);
    ht.Add(i, tmpEmployee);
  }
  for (var i = 1; i <= ht.Count; i++) {
    alert(ht.GetValue(i).userName); //其实等价于ht.ObjArr[i].userName
    //alert(ht.ObjArr[i].userName);
  }
  ht.Remove(1);
  alert(ht.Contains(1)); //false
  alert(ht.Contains(2)); //true
  //alert(ht.GetValue(1)); //异常
  var result = ht.GetValue(2);
  if (result != null) {
    alert("Employee Id:" + result.id + ";UserName:" + result.userName);
  }
  ht.Add(2, "这一个key已经存在!"); //Add无效
  //ht.Clear(); //清空
  alert(ht.Count);
}

Array.prototype.maxNum = function(){
  var arr = this,obj={};
  for(var i =0, len=arr.length;i<len;i++){
    var key = arr[i];
    if( ! obj[key]){
      obj[key] = 1;
    }else{
      obj[key]++;
    }
  }
  var max = -1,maxStr;
  for( key in obj){
    if(obj[key]>max){
      max = obj[key];
      maxStr = key;
    }
  }
  //alert(maxStr);
  return [maxStr,max];
}