JavaScript中利用Array和Object实现Map的方法

本文实例讲述了Javascript中利用Array和Object实现Map的方法。分享给大家供大家参考。具体如下：

昨天突然看到以前别人用Javascript实现的Map感觉很不错，但是发现有个别方法有问题，顺便完善了下，添加了 remove 、indexOf 、values、clear等方法。

function Map(){
  this.keys = new Array(); 
  this.data = new Object();
  var toString = Object.prototype.toString;
  
  this.size = function(){
    return this.keys.length;
  }
  
  this.put = function(key, value){
    if(this.data[key] == null){
      this.data[key] = value;
    }
    this.keys.push(key);
  }
  
  this.get = function(key){
    return this.data[key];
  }
  
  this.remove = function(key){
    var index = this.indexOf(key);
    if(index != -1){
      this.keys.splice(index, 1);
    }
    this.data[key] = null;
  }
  
  this.clear = function(){
    for(var i=0, len = this.size(); i < len; i++){
      var key = this.keys[i];
      this.data[key] = null;
    }
    this.keys.length = 0;
  }
  
  this.containsKey = function(key){
    return this.data[key] != null;
  }
  
  this.isEmpty = function(){
    return this.keys.length === 0;
  }
  
  this.entrySet = function(){
    var size = this.size();
    var datas = new Array(size);
    for (var i = 0, len = size; i < len; i++) {
      var key = this.keys[i];
      var value = this.data[key];
      datas[i] = {
 'key' : key,
 'value':value  
      }
    }
    return datas;
  }
  
  this.each = function(fn){
    if(toString.call(fn) === '[object Function]'){
      for (var i = 0, len = this.size(); i < len; i++) {
 var key = this.keys[i];
 fn(i, key, this.data[key]);
      }
    }
    return null;
  }
  
  this.indexOf = function(key){
    var size = this.size();
    if(size > 0){
      for(var i=0, len=size; i < len; i++){
 if(this.keys[i] == key)
 return i;
      }
    }
    return -1;
  }
  
  this.toString = function(){
    var str = "{";
    for (var i = 0, len = this.size(); i < len; i++, str+=",") {
      var key = this.keys[i];
      var value = this.data[key];
      str += key + "=" + value; 
    }
    str = str.substring(0, str.length-1);
    str += "}";
    return str;
  }
  
  this.values = function(){
    var size = this.size();
    var values = new Array();
    for(var i = 0; i < size; i++){
      var key = this.keys[i];
      values.push(this.data[key]);
    }
    return values;
  }
}

希望本文所述对大家的javascript程序设计有所帮助。