题解 | 求四位数各个数位之和

const rl = require('readline').createInterface({input: process.stdin})
const iter = rl[Symbol.asyncIterator]()
const readline = async () => (await iter.next()).value

// 方法3：数组解构法
function sumDigits3(n) {
    const [a, b, c, d] = String(n).split('').map(Number);
    return a + b + c + d;
}

void async function () {
    const num = parseInt(await readline())
    if (num >= 1000 && num <= 9999) {

        console.log(sumDigits3(num))

    }else{
        console.log('输入数据不符合范围')
    }
    rl.close()
}()