JavaScript Map数据结构

 Array.prototype.remove = function (s) {
     for (var i = 0; i < this.length; i++) {
         if (s == this[i])
             this.splice(i, 1);
     }
 }

 /**
  * Simple Map
  *
  *
  * var m = new Map(); m.put('key','value'); ... var s = "";
  * m.each(function(key,value,index){ s += index+":"+ key+"="+value+"\n"; });
  * alert(s);
  *
  * @author dewitt
  * @date 2008-05-24
  */
 function Map() {
     /** 存放键的数组(遍历用到) */
     this.keys = new Array();
     /** 存放数据 */
     this.data = new Object();

     this.maxSize = arguments[0] ? arguments[0] : 0;

     /**
      * 放入一个键值对
      *
      * @param {String}
      *            key
      * @param {Object}
      *            value
      */
     this.put = function (key, value) {
         if (this.data[key] == null) {
             this.keys.push(key);
         }
         this.data[key] = value;
     };

     /**
      * 放入一个键值对, FIFO容量移除策略
      *
      * @param {String}
      *            key
      * @param {Object}
      *            value
      */
     this.putQ = function (key, value) {
         if (this.data[key] == null) {
             this.keys.push(key);
         }
         this.data[key] = value;
         this.trimToSize(this.maxSize);
     };

     this.trimToSize = function (max_size) {
         var tmpSize = this.size;
         if (tmpSize > max_size) {
             this.each(function (key, value, index) {
                 if (index < tmpSize - max_size) {
                     this.remove(key);
                 }
             });
         }
     }

     /**
      * 获取某键对应的值
      *
      * @param {String}
      *            key
      * @return {Object} value
      */
     this.get = function (key) {
         return this.data[key];
     };

     /**
      * 删除一个键值对
      *
      * @param {String}
      *            key
      */
     this.remove = function (key) {
         this.keys.remove(key);
         this.data[key] = null;
     };

     /**
      * 遍历Map,执行处理函数
      *
      * @param {Function}
      *            回调函数 function(key,value,index){..}
      */
     this.each = function (fn) {
         if (typeof fn != 'function') {
             return;
         }
         var len = this.keys.length;
         for (var i = 0; i < len; i++) {
             var k = this.keys[i];
             fn(k, this.data[k], i);
         }
     };

     /**
      * 获取键值数组(类似Java的entrySet())
      *
      * @return 键值对象{key,value}的数组
      */
     this.entrys = function () {
         var len = this.keys.length;
         var entrys = new Array(len);
         for (var i = 0; i < len; i++) {
             entrys[i] = {
                 key: this.keys[i],
                 value: this.data[i]
             };
         }
         return entrys;
     };

     /**
      * 判断Map是否为空
      */
     this.isEmpty = function () {
         return this.keys.length == 0;
     };

     /**
      * 获取键值对数量
      */
     this.size = function () {
         return this.keys.length;
     };

     /**
      * 重写toString
      */
     this.toString = function () {
         var s = "{";
         for (var i = 0; i < this.keys.length; i++, s += ',') {
             var k = this.keys[i];
             s += k + "=" + JSON.stringify(this.data[k]);
         }
         s += "}";
         return s;
     };
 }

 function testMap() {
     var m = new Map();
     m.put('key1', 'v1');
     m.put('key2', 'v2');
     m.put('key3', 'v3');
     m.put('key4', 'v4');
     alert("init:" + m);

     m.put('key1', 'v5');
     alert("set key1:" + m);

     m.remove("key2");
     alert("remove key2: " + m);

     var s = "";
     m.each(function (key, value, index) {
         if (index < 2) {
             m.remove(key);
         }
     });

     m.each(function (key, value, index) {
         s += index + ":" + key + "=" + value + "\n";
     });
     alert(s);
 }

prototype是原型，通过原型调用方法，后续会总结一下。

　

　整个map相当于一个json对象,map = {keys : arr,values : abc,}  就是这种形式。通过map来存取数据，但不能存储大数据。

这就是数据结构，太重要了。