Javascript 我怎样才能洗牌一个数组？
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How can I shuffle an array?
提问by Anshul
I want to shuffle an array of elements in JavaScript like these:
我想对 JavaScript 中的元素数组进行洗牌，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]
回答by Jeff
Use the modern version of the Fisher–Yates shuffle algorithm:
使用现代版本的 Fisher-Yates shuffle 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) version
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;
}
Note however, that swapping variables with destructuring assignmentcauses significant performance loss, as of October 2017.
但是请注意，截至 2017 年 10 月，使用解构赋值交换变量会导致显着的性能损失。
Use
用
var myArray = ['1','2','3','4','5','6','7','8','9'];
shuffle(myArray);
Implementing prototype
实现原型
Using Object.defineProperty(method taken from this SO answer) we can also implement this function as a prototype method for arrays, without having it show up in loops such as for (i in arr). The following will allow you to call arr.shuffle()to shuffle the array arr:
使用Object.defineProperty（取自this SO answer的方法）我们还可以将此函数实现为数组的原型方法，而无需将其显示在诸如for (i in arr). 以下将允许您调用arr.shuffle()以重新排列数组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;
}
});
回答by Blender
You could use the Fisher-Yates Shuffle(code adapted from this site):
您可以使用Fisher-Yates Shuffle（代码改编自本网站）：
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;
}
