我有一个这样的数组：
var arr1 = ["a", "b", "c", "d"];
我如何随机化/打乱它？
当前回答
使用ES6功能的现代短内联解决方案：
['a','b','c','d'].map(x => [Math.random(), x]).sort(([a], [b]) => a - b).map(([_, x]) => x);
（出于教育目的）
其他回答
对CoolAJ86答案的简单修改，不修改原始数组：
/**
* Returns a new array whose contents are a shuffled copy of the original array.
* @param {Array} The items to shuffle.
* https://stackoverflow.com/a/2450976/1673761
* https://stackoverflow.com/a/44071316/1673761
*/
const shuffle = (array) => {
let currentIndex = array.length;
let temporaryValue;
let randomIndex;
const newArray = array.slice();
// While there remains elements to shuffle...
while (currentIndex) {
randomIndex = Math.floor(Math.random() * currentIndex);
currentIndex -= 1;
// Swap it with the current element.
temporaryValue = newArray[currentIndex];
newArray[currentIndex] = newArray[randomIndex];
newArray[randomIndex] = temporaryValue;
}
return newArray;
};
使用ES6功能的现代短内联解决方案：
['a','b','c','d'].map(x => [Math.random(), x]).sort(([a], [b]) => a - b).map(([_, x]) => x);
（出于教育目的）
虽然已经建议了许多实现，但我觉得我们可以使用forEach循环使其更短、更容易，因此我们不必担心计算数组长度，也可以安全地避免使用临时变量。
var myArr = ["a", "b", "c", "d"];
myArr.forEach((val, key) => {
randomIndex = Math.ceil(Math.random()*(key + 1));
myArr[key] = myArr[randomIndex];
myArr[randomIndex] = val;
});
// see the values
console.log('Shuffled Array: ', myArr)
//doesn change array
Array.prototype.shuffle = function () {
let res = [];
let copy = [...this];
while (copy.length > 0) {
let index = Math.floor(Math.random() * copy.length);
res.push(copy[index]);
copy.splice(index, 1);
}
return res;
};
let a=[1, 2, 3, 4, 5, 6, 7, 8, 9];
console.log(a.shuffle());
使用Ramda的功能解决方案。
const {map, compose, sortBy, prop} = require('ramda')
const shuffle = compose(
map(prop('v')),
sortBy(prop('i')),
map(v => ({v, i: Math.random()}))
)
shuffle([1,2,3,4,5,6,7])
