javascript 数据结构----集合

function Set() {
            var items = {};
            this.has = function (value) {
                // return value in items 
                return items.hasOwnProperty(value)
            }
            this.add = function (value) {
                if (!this.has(value)) {
                    items[value] = value
                    return true
                }
                return false
            }
            this.remove = function (value) {
                if (this.has(value)) {
                    delete items[value]
                    return true
                }
                return false
            }
            this.clear = function () {
                items = {}
            }
            this.size = function () {
                return Object.keys(items).length // es5 以上版本
            }
            this.sizeLegacy = function () {
                var count = 0;
                for (var prop in items) { //{5}
                    if (items.hasOwnProperty(prop)) //{6}
                        ++count; //{7}
                }
                return count;
            };
            this.values = function () {
                return Object.keys(items);
            };
            this.valuesLegacy = function () {
                var keys = [];
                for (var key in items) { //{7}
                    keys.push(key); //{8}
                }
                return keys;
            };
            // 并集
            this.union = function (otherSet) {
                var unionSet = new Set()

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

                values = otherSet.values()
                for (var j = 0; j < values.length; j++) {
                    unionSet.add(values[j])
                }
                return unionSet

            }
            // 交集
            this.intersection = function (otherSet) {
                var intersectionSet = new Set(); //{1}
                var values = this.values();
                for (var i = 0; i < values.length; i++) { //{2}
                    if (otherSet.has(values[i])) {    //{3}
                        intersectionSet.add(values[i]); //{4}
                    }
                }
                return intersectionSet;
            }
            // 差集
            this.difference = function (otherSet) {
                var differenceSet = new Set(); //{1}
                var values = this.values();
                for (var i = 0; i < values.length; i++) { //{2}
                    if (!otherSet.has(values[i])) {
                        differenceSet.add(values[i]); //{4}
                    }
                }
                return differenceSet;  //{3}
            }
            // 子集
            this.subset = function (otherSet) {
                if (this.size() > otherSet.size()) { //{1}
                    return false;
                } else {
                    var values = this.values();
                    for (var i = 0; i < values.length; i++) { //{2}
                        if (!otherSet.has(values[i])) { //{3}
                            return false; //{4}
                        }
                    }
                    return true; //{5}
                }
            }
        }
        // var set = new Set();
        // set.add(1); console.log(set.values()); //输出["1"] 
        // console.log(set.has(1)); //输出true 
        // console.log(set.size()); //输出1
        // set.add(2);
        // console.log(set.values()); //输出["1", "2"] 
        // console.log(set.has(2)); //true 
        // console.log(set.size()); //2


        // 并集

        var setA = new Set();
        setA.add(1);
        setA.add(2);
        setA.add(3);
        var setB = new Set();
        setB.add(3);
        setB.add(4);
        setB.add(5)
        setB.add(6)
        var unionAB = setA.union(setB)
        console.log(unionAB.values())
        // 交集
        var intersectionAB = setA.intersection(setB);
        console.log(intersectionAB.values());
        //差集
        var differenceAB = setA.difference(setB);
        console.log(differenceAB.values());