学习链接

数组乱序

function shuffle(arr) {
    let new_arr = arr.map(i => ({ v: i, r: Math.random() }));
    new_arr.sort((a, b) => a.r - b.r);
    arr.splice(0, arr.length, ...new_arr.map(i => i.v));
    return arr;
}

function shuffle(arr) {
    let i = arr.length;
    while (i) {
        let j = Math.floor(Math.random() * i--);
        [arr[j], arr[i]] = [arr[i], arr[j]];
    }
    return arr;
}

function shuffle(arr) {
    const len = arr.length;
    for (let i = 0; i < len; i++) {
        let j = Math.floor(Math.random() * (len - i)) + i;
        [arr[j], arr[i]] = [arr[i], arr[j]];
    }
    return arr;
}

概率测试

let times = 100000;
let res = {};
for (let i = 0; i < times; i++) {
    let arr = shuffle([1, 2, 3]);
    let key = JSON.stringify(arr);
    res[key] ? res[key]++ : res[key] = 1;
}
// 为了方便展示，转换成百分比
for (let key in res) {
    res[key] = res[key] / times * 100 + '%'
}
console.log(res);