function shuffle(array) {
let counter = array.length;
// While there are elements in the array
while (counter > 0) {
// Pick a random index
let index = Math.floor(Math.random() * counter);
// Decrease counter by 1
counter--;
// And swap the last element with it
let temp = array[counter];
array[counter] = array[index];
array[index] = temp;
}
return array;
}
/**
* 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;
}
您可以使用Fisher-Yates Shuffle(代码改编自此网站):
function shuffle(array) { let counter = array.length; // While there are elements in the array while (counter > 0) { // Pick a random index let index = Math.floor(Math.random() * counter); // Decrease counter by 1 counter--; // And swap the last element with it let temp = array[counter]; array[counter] = array[index]; array[index] = temp; } return array; }使用现代版本的 Fisher–Yates 洗牌算法:
/** * 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,使用解构交换变量截至 2017 年 10 月, 分配会导致严重的性能损失。
使用
实现原型
使用
Object.defineProperty(取自此SO答案的方法)我们还可以实现该函数作为数组的原型方法,而无需让它出现在诸如for (i in arr)之类的循环中。以下代码将允许您调用arr.shuffle()来随机排列数组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; } });