javascript - 递归挑战 - Edabit

Question

问题要我输出字符串“Edabit”，其中“a”字符的数量等于通过函数传递的初始数字。
我尝试了不同的连接方法，但由于某种原因，“a”字符串似乎忽略了它们在连接中的位置。

function howManyTimes(num) {
    let str = ''
    
    if (num === 0){
        return `Ed${str}bit`
    }
    else {
        str += 'a'
        return str += howManyTimes(num - 1)
    }
}

console.assert(howManyTimes(0) == "Edbit", "1. Instead got "+howManyTimes(0));
console.assert(howManyTimes(1) == "Edabit", "2. Instead got "+howManyTimes(1));
console.assert(howManyTimes(10) == "Edaaaaaaaaaabit", "3. Instead got "+howManyTimes(10));

Answer 1

function howManyTimes(num, str) {
  if (!str) str = '';
  
  if (num > 0) {
    return howManyTimes(num - 1, str + 'a');
  } else {
    return `Ed${str}bit`;
  }
}

console.log(howManyTimes(8));

一个问题是您的递归总是将方法的结果附加到 a .而不是这样做，传递聚合的字符串，然后在到达末尾时使用。