Answer 1

你这例子不对吧？你的 setTimeout 在 new Promise 内部呀，大兄弟；setTimeout 不执行 then 也永远不执行，这是有明显的先后顺序的

Answer 2

我们没有必要遍历所有数，只需遍历1-99就行了，
然后对1-99 的所有数进行对称一次，
分别找到对称后为奇数长度的和对称后为偶数长度的所有数

`
 function getPalind(){
    let res = []
    for (let i = 1; i <= 99; i++) {
        res.push(palind(i, false))
    }
    for (let i = 10; i <= 99; i++) {
        res.push(palind(i, true))
    }
    return res
 }

function palind(str, single){
    str = str + ''
    let res = '', end = str.length -  Number(single) - 1
    for (let i = end; i >= 0; i--) {
        str += str[i]
    }
    return +str
}

`

Answer 3

const value = '112'
const fn = (value) => {
let vals = value.split('');
//1 11 112
for (let i = 0; i < vals.length; i++) {
let v = vals.slice(0,i+1).join('')
console.log(v)
}
}
fn(value)

Answer 4

function poker(array = []) {
    let origin = [];
    while (array.length !== 0) {
        if (origin.length > 0) {
            origin.push(origin.shift());
        }
        origin.push(array.pop());
    }
    return origin;
}

console.log(poker([1,2,3,4,5,6,7,8,9,10,11,12,13]));

//[7, 10, 6, 13, 5, 9, 4, 11, 3,  8, 2, 12, 1]