https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/basic-javascript/use-recursion-to-create-a-countdown

We have defined a function called countdown with one parameter (n). The function should use recursion to return an array containing the integers n through 1 based on the n parameter. If the function is called with a number less than 1, the function should return an empty array. For example, calling this function with n = 5 should return the array [5, 4, 3, 2, 1]. Your function must use recursion by calling itself and must not use loops of any kind.

    // Only change code below this line
   

     function countdown(n){
          if (n<1)
          return [];
          else{
            const numbArray = countdown(n-1);
            numbArray.push(n)
            return numbArray;
          }
        }
        console.log(countdown(5))
    // Only change code above this line

comes out like [1 2 3 4 5] instead of [5 4 3 2 1]

I've been breaking my mind forever then I have completed it with the unshift method but felt like it wanted to me use push even though that sends data to the end of the stack

CodePudding user response：

 function countdown(max,currentN){
      if (currentN > max)
      return [];
      else if(currentN <= max){
   const numbArray = countdown(max,currentN 1);
        numbArray.push(currentN)
        return numbArray;
      }
    }
    console.log(countdown(5,1))
// Only change code above this line

basically it just counts up to the end value given at start

CodePudding user response：

else {
 const arr = []
 arr.push(n)
 return arr.concat(countdown(n-1))
}

you can use this code replace, y question reason is y not understand recursion, try to break the point and watch the function execution step by step in the browser or vscode