Can someone explain for me how this recursion works?

Question

This is multiplication function that takes an array and n numbers of elements in the array and returns the multiplication of the N numbers of element in the array.

function multiply(arr, n) {
        if (n <= 0) 
        return 1;
        let first = multiply(arr, n - 1);
        console.log(`first value: ${first}`);
        console.log(typeof(first))
        let second = arr[n - 1];
        let result = first * second;
        return result;
      }
     const mul = multiply([1,2,3],2);
      console.log(mul)

How this recursion replace for or while loop?

Relevant: [Understanding how recursive functions work](https://stackoverflow.com/q/25676961) — VLAZ, Sep 13 '22 at 09:39
Take a pen and paper to trace the iteration. Create nodes and it is fairly easy to understand. — Ramsudharsan Manoharan, Sep 13 '22 at 10:49

score 1 · Answer 1 · answered Sep 13 '22 at 13:36

The function multiply multiplies the last element of an array with n elements, i.e. arr[n-1] with the product of the previous elements of that array.

The "product of the previous elements" is calculated using multiply itself.

The recursion ends as soon as there are no elements left in the array. Then 1 is taken as the initial factor for the multiplication.

Can someone explain for me how this recursion works?

1 Answers1