如何打乱数组？ [复制]

我想在 JavaScript 中打乱数组元素，如下所示：

[0, 3, 3] -> [3, 0, 3]
[9, 3, 6, 0, 6] -> [0, 3, 6, 9, 6]
[3, 3, 6, 0, 6] -> [0, 3, 6, 3, 6]

Use Fisher-Yates 洗牌算法的现代版本 https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle#The_modern_algorithm:

/**
 * Shuffles array in place.
 * @param {Array} a items An array containing the items.
 */
function shuffle(a) {
    var j, x, i;
    for (i = a.length - 1; i > 0; i--) {
        j = Math.floor(Math.random() * (i + 1));
        x = a[i];
        a[i] = a[j];
        a[j] = x;
    }
    return a;
}

ES2015（ES6）版本

/**
 * Shuffles array in place. ES6 version
 * @param {Array} a items An array containing the items.
 */
function shuffle(a) {
    for (let i = a.length - 1; i > 0; i--) {
        const j = Math.floor(Math.random() * (i + 1));
        [a[i], a[j]] = [a[j], a[i]];
    }
    return a;
}

但请注意，交换变量解构赋值 https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment#Swapping_variables截至 2017 年 10 月，导致显着的性能损失。

Use

var myArray = ['1','2','3','4','5','6','7','8','9'];
shuffle(myArray);

实施原型

Using Object.defineProperty (取自此 SO 答案的方法 https://stackoverflow.com/a/30391923/1256925）我们还可以将此函数实现为数组的原型方法，而无需让它出现在循环中，例如for (i in arr)。以下将允许您致电arr.shuffle()打乱数组arr:

Object.defineProperty(Array.prototype, 'shuffle', {
    value: function() {
        for (let i = this.length - 1; i > 0; i--) {
            const j = Math.floor(Math.random() * (i + 1));
            [this[i], this[j]] = [this[j], this[i]];
        }
        return this;
    }
});