[js] 数组去重、交集、并集

去重

            function array_unique(arr) {
                var result = [arr[0]],
                    isRepeat;
                for (var i = 0; i < arr.length; i++) {
                    isRepeat = false;
                    for (var j = 0; j < result.length; j++) {
                        if (result[j] === arr[i]) {
                            isRepeat = true;
                            break;
                        }
                    }
                    if (!isRepeat) {
                        result.push(arr[i]);
                    }
                }
                return result;
            }

 

取重

            function array_repeat(arr) {
                var result = [],
                    length = arr.length;
                for (var i = 0; i < length; i++) {
                    for (j = i + 1; j < length; j++) {
                        if (arr[i] === arr[j]) {
                            result.push(arr[i]);
                        }
                    }
                }
                return array_unique(result);
            }
            console.warn(array_repeat([4, 3, 2, 1, 6, 6, 1, 2, 3, 4, 5]));
            console.warn(array_repeat([4, 3, 2, 1, 5, 2, '5', 1, 2, 3, 4, 5, 3]));

 

取差,删除重复元素

            function array_difference(arr) {
                var result = [],
                    length = arr.length,
                    l;
                for (var i = 0; i < length; i++) {
                    for (j = 0; j < length; j++) {
                        if (arr[i] === arr[j]) {
                            result.push(j);
                        }
                    }
                }
                
                l = array_unique(result).length;
                for (var i = 0; i < l; i++) {
                    var k = result[i];
                    delete arr[k];
                }
                return arr;
            };
            console.warn(array_difference([4, 3, 2, 1, 6, 6, 1, 2, 3, 4, 5]));
            console.warn(array_difference([4, 3, 2, 1, 5, 2, '5', 1, 2, 3, 4, 5, 3]));

 

并集

            function array_union(arr1, arr2) {
                var a1 = array_unique(arr1),
                    a2 = array_unique(arr2),
                    c = a1.concat(a2);
                return array_unique(c);
            };
            console.log(array_union([4, 3, 2, 1, 6, 6], [1, 2, 3, 4, 5]));
            console.log(array_union([4, 3, 2, 1, 5, 2], ['5', 1, 2, 3, 4, 5, 3]));

 

交集

            function array_intersection(arr1, arr2) {
                var a1 = array_unique(arr1),
                    a2 = array_unique(arr2),
                    c = a1.concat(a2);
                return array_repeat(c);
            };
            console.log(array_intersection([4, 3, 2, 1, 6, 6], [1, 2, 3, 4, 5]));
            console.log(array_intersection([4, 3, 2, 1, 5, 2], ['5', 1, 2, 3, 4, 5, 3]));

 差集

            function array_diff(a, b) {
                var temp = [],
                    status;
                for (var i = 0; i < a.length; ++i) {
                    status = true;
                    for (var j = 0; j < b.length; ++j) {
                        if (a[i] === b[j]) {
                            status = false;
                            break;
                        }
                    }
                    if (status) {
                        temp.push(a[i]);
                    }
                }
                return temp;
            }

 

Array.prototype.indexOf 兼容方法

            if (!Array.prototype.indexOf) {
                Array.prototype.indexOf = function(searchElement, fromIndex) {
                    var k;
                    if (this == null) {
                        throw new TypeError('"this" is null or not defined');
                    }
                    var O = Object(this);
                    var len = O.length >>> 0;
                    if (len === 0) {
                        return -1;
                    }
                    var n = +fromIndex || 0;
                    if (Math.abs(n) === Infinity) {
                        n = 0;
                    }
                    if (n >= len) {
                        return -1;
                    }
                    k = Math.max(n >= 0 ? n : len - Math.abs(n), 0);
                    while (k < len) {
                        if (k in O && O[k] === searchElement) {
                            return k;
                        }
                        k++;
                    }
                    return -1;
                };
            }

 # ES5去重

function array_diff(a, b) {
  return a.filter(function(x) { return b.indexOf(x) == -1; });
}