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1：字符串转换法
function sumDigits1(n) {
    const digits = String(n).split('');
    return digits.reduce((sum, digit) => sum + Number(digit), 0);
}

void async function () {
    const num = parseInt(await readline())
    if (num >= 1000 && num <= 9999) {
        console.log(sumDigits1(num))

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