js数组方法的记录

forEach方法:

Array.prototype.myForEach = function (func, obj) {
    var len = this.length;
    var _this = arguments[1] ? arguments[1] : window;
    // var _this=arguments[1]||window;
    for (var i = 0; i < len; i++) {
        func.call(_this, this[i], i, this)
    }
}

filter方法：

Array.prototype.myFilter = function (func, obj) {
    var len = this.length;
    var arr = [];
    var _this = arguments[1] || window;
    for (var i = 0; i < len; i++) {
        func.call(_this, this[i], i, this) && arr.push(this[i]);
    }
    return arr;
}

map方法

Array.prototype.myMap = function (func) {
    var arr = [];
    var len = this.length;
    var _this = arguments[1] || window;
    for (var i = 0; i < len; i++) {
        arr.push(func.call(_this, this[i], i, this));
    }
    return arr;
}

every方法

Array.prototype.myEvery = function (func) {
    var flag = true;
    var len = this.length;
    var _this = arguments[1] || window;
    for (var i = 0; i < len; i++) {
        if (func.apply(_this, [this[i], i, this]) == false) {
            flag = false;
            break;
        }
    }
    return flag;
}

reduce方法

Array.prototype.myReduce = function (func, initialValue) {
    var len = this.length,
        nextValue,
        i;
    if (!initialValue) {
        // 没有传第二个参数
        nextValue = this[0];
        i = 1;
    } else {
        // 传了第二个参数
        nextValue = initialValue;
        i = 0;
    }
    for (; i < len; i++) {
        nextValue = func(nextValue, this[i], i, this);
    }
    return nextValue;
}

数组排序

// 快排 [left] + min + [right]
function quickArr(arr) {
    if (arr.length <= 1) {
        return arr;
    }
    var left = [],
        right = [];
    var pIndex = Math.floor(arr.length / 2);
    var p = arr.splice(pIndex, 1)[0];
    for (var i = 0; i < arr.length; i++) {
        if (arr[i] <= p) {
            left.push(arr[i]);
        } else {
            right.push(arr[i]);
        }
    }
    // 递归
    return quickArr(left).concat([p], quickArr(right));
}

// 冒泡
function bubbleSort(arr) {
    for (var i = 0; i < arr.length - 1; i++) {
        for (var j = i + 1; j < arr.length; j++) {
            if (arr[i] > arr[j]) {
                var temp = arr[i];
                arr[i] = arr[j];
                arr[j] = temp;
            }
        }
    }
    return arr;
}

function bubbleSort(arr) {
    var len = arr.length;
    for (var i = 0; i < len - 1; i++) {
        for (var j = 0; j < len - 1 - i; j++) {
            if (arr[j] > arr[j + 1]) {
                var temp = arr[j];
                arr[j] = arr[j + 1];
                arr[j + 1] = temp;
            }
        }
    }
    return arr;
}