js Array 交集 並集 差集 去重

標籤：

最勁項目需要用到js數組去重和交集的一些運算，我的數組元素個數可能到達1000以上，網上的實現方式都是2次迴圈，效能不適合我的需求，1000*1000那迴圈次數太多了，所以我這裡採用對象object來做處理，用空間換時間，code 如下：

  ///集合取交集        Array.intersect = function () {            var result = new Array();            var arrCount = arguments.length;/*數組個數,預設2個數組取交集*/            if (arrCount <= 1) { return; }            var type = typeof (arguments[0][0]);            for (var k = 1; k < arrCount; k++) {                if (arguments[k].length < 1) {                    return;//每個數組都要有值                }                if (type != typeof (arguments[k][0])) {//每個數組元素類型相同                    return;                }            }            var obj = {};            for (var i = 0; i < arrCount; i++) {                var arr = arguments[i];                for (var j = 0; j < arr.length; j++) {                    if (!obj[arr[j]]) {                        obj[arr[j]] = 1;                    }                    else {                        obj[arr[j]]++;                    }                }            }            for (var num in obj) {                if (obj[num] == arrCount) {                    if (type == typeof (0)) {                        result.push(num - 0);                    }                    else {                        result.push(num);                    }                }            }            return result;        }        Array.prototype.intersect = function (arr) {            Array.intersect(this, arr);        }        //集合去掉重複        Array.prototype.uniquelize = function () {            var tmp = {},                ret = [];            for (var i = 0, j = this.length; i < j; i++) {                if (!tmp[this[i]]) {                    tmp[this[i]] = 1;                    ret.push(this[i]);                }            }            return ret;        }        //並集        Array.union = function () {            var arrCount = arguments.length;/*數組個數,預設2個數組取交集*/            if (arrCount <= 1) { return; }            var type = typeof (arguments[0][0]);            for (var k = 1; k < arrCount; k++) {                if (arguments[k].length < 1) {                    return;//每個數組都要有值                }                if (type != typeof (arguments[k][0])) {//每個數組元素類型相同                    return;                }            }            var temp = arguments[0];            var arrCount = temp.length;            for (var i = 1; i < arguments.length; i++) {                var arr = arguments[i];                if (i > 1) {                    arrCount += arr.length;                }                for (var j = 0; j < arr.length; j++) {                    temp[arrCount + j] = arr[j];                }            }            temp = temp.uniquelize();//去掉重複            return temp;        }        Array.prototype.union = function (ar) {            Array.union(this, ar);        }        //2個集合的差集 在arr不存在        Array.prototype.minus = function (arr) {            var result = new Array();            var obj = {};            var type = typeof (this[0]);            for (var i = 0; i < this.length; i++) {                obj[this[i]] = true;            }            for (var i = 0; i < arr.length; i++) {                if (obj[arr[i]]) {                    obj[arr[i]] = false;                }            }            for (var num in obj) {                if (obj[num]) {                    if (type == typeof (0)) {                        result.push(num - 0);                    }                    else {                        result.push(num);                    }                }            }            return result;        };        console.log(Array.intersect(["1", "2", "3"], ["2", "3", "4", "5", "6"]));//[2,3]        console.log([1, 2, 3, 2, 3, 4, 5, 6].uniquelize());//[1,2,3,4,5,6]        console.log(Array.union(["1", "2", "3"], ["2", "3", "4", "5", "6"], ["5", "6", "7", "8", "9"]))        console.log(["2", "3", "4", "5", "6"].minus(["1", "2", "3"]));

 

js Array 交集 並集 差集 去重