js Array 交集 并集 差集 去重

集合取交集

//集合取交集
Array.intersect = function () {
    var result = new Array();
    var obj = {};
    for (var i = 0; i < arguments.length; i++) {
        for (var j = 0; j < arguments[i].length; j++) {
            var str = arguments[i][j];
            if (!obj[str]) {
                obj[str] = 1;
            }
            else {
                obj[str]++;
                if (obj[str] == arguments.length)
                {
                    result.push(str);
                }
            }//end else
        }//end for j
    }//end for i
    return result;
}
console.log(Array.intersect(["1", "2", "3"], ["2", "3", "4", "5", "6"]));//[2,3]

集合去掉重复

//集合去掉重复
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;
}
console.log([1, 2, 3, 2, 3, 4, 5, 6].uniquelize());//[1,2,3,4,5,6]

并集

//并集
Array.union = function () {
    var arr = new Array();
    var obj = {};
    for (var i = 0; i < arguments.length; i++) {
        for (var j = 0; j < arguments[i].length; j++)
        {
            var str=arguments[i][j];
            if (!obj[str])
            {
                obj[str] = 1;
                arr.push(str);
            }
        }//end for j
    }//end for i
    return arr;
}
console.log(Array.union(["1", "2", "3"], ["2", "3", "4", "5", "6"], ["5", "6", "7", "8", "9"]))

连个集合的差集 在arr不存在

//2个集合的差集 在arr不存在
Array.prototype.minus = function (arr) {
    var result = new Array();
    var obj = {};
    for (var i = 0; i < arr.length; i++) {
        obj[arr[i]] = 1;
    }
    for (var j = 0; j < this.length; j++) {
        if (!obj[this[j]])
        {
            obj[this[j]] = 1;
            result.push(this[j]);
        }
    }
    return result;
};
console.log(["2", "3", "4", "5", "6"].minus(["1", "2", "3"]));

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