记录Javascript集合操作

 　　function Set() {
         var items = {};
         /**
          * 添加元素
          * @param {[type]} value [description]
          */
         this.add = function(value) {
             if (!this.has(value)) {
                 items[value] = value;
                 return true;
             }
             return false;
         };
         /**
          * 删除元素
          * @param  {[type]} value [description]
          * @return {[type]}       [description]
          */
         this.remove = function(value) {
             if (this.has(value)) {
                 delete items[value];
                 return true;
             }
             return false;
         };
         /**
          * 判断元素是否存在集合里
          * @param  {[type]}  value [description]
          * @return {Boolean}       [description]
          */
         this.has = function(value) {
             return items.hasOwnProperty(value);
         };
         /**
          * 清空集合
          * @return {[type]} [description]
          */
         this.clear = function() {
             items = {};
         };
         /**
          * 获取集合的长度
          * @return {[type]} [description]
          */
         this.size = function() {
             return Object.keys(items).length;
         };
         /**
          * 获取集合的长度（兼容IE8）
          * @return {[type]} [description]
          */
         this.sizeLegacy = function() {
             var count = 0;
             for (var prop in items) {
                 if (items.hasOwnProperty(prop))
                     ++count;
             }
             return count;
         };
         /**
          * 获取集合
          * @return {[type]} [description]
          */
         this.values = function() {
             return Object.keys(items);
         };
         /**
          * 获取集合（兼容IE8）
          * @return {[type]} [description]
          */
         this.valuesLegacy = function() {
             var keys = [];
             for (var key in items) {
                 keys.push(key);
             }
             return keys;
         };
         /**
          * 并集
          * @param  {[type]} otherSet [description]
          * @return {[type]}          [description]
          */
         this.union = function(otherSet) {
             var unionSet = new Set();

             var values = this.valuesLegacy();
             for (var i = 0; i < values.length; i++) {
                 unionSet.add(values[i]);
             }

             values = otherSet.valuesLegacy();
             for (var i = 0; i < values.length; i++) {
                 unionSet.add(values[i]);
             }
             return unionSet;
         };
         /**
          * 交集
          * @param  {[type]} otherSet [description]
          * @return {[type]}          [description]
          */
         this.intersection = function(otherSet) {
             var intersectionSet = new Set();

             var values = this.valuesLegacy();
             for (var i = 0; i < values.length; i++) {
                 if (otherSet.has(values[i])) {
                     intersectionSet.add(values[i]);
                 }
             }

             return intersectionSet;
         };
         /**
          * 差集
          * @param  {[type]} otherSet [description]
          * @return {[type]}          [description]
          */
         this.difference = function(otherSet) {
             var differenceSet = new Set();

             var values = this.valuesLegacy();
             for (var i = 0; i < values.length; i++) {
                 if (!otherSet.has(values[i]))
                     differenceSet.add(values[i]);
             }
             return differenceSet;
         };
         /**
          * 子集
          * @param  {[type]} otherSet [description]
          * @return {[type]}          [description]
          */
         this.subset = function(otherSet) {
             if (this.sizeLegacy() > otherSet.sizeLegacy()) {
                 return false;
             } else {
                 var values = this.valuesLegacy();
                 for (var i = 0; i < values.length; i++) {
                     if (!otherSet.has(values[i])) {
                         return false;
                     }
                 }
                 return true;
             }
         }
     }

     var set = new Set();
     set.add(1);
     set.add(2);
     set.add(3);

     var set1 = new Set();
     set1.add(3);
     set1.add(4);
     set1.add(5);

     var set2 = new Set();
     set2.add(3);

     var unionSet = set.union(set1);
     console.log(unionSet.valuesLegacy());

     var intersectionSet = set.intersection(set1);
     console.log(intersectionSet.valuesLegacy());

     var differenceSet = set.difference(set1);
     console.log(differenceSet.valuesLegacy());

     console.log(set.subset(set1));
     console.log(set2.subset(set));