Recursion in this specific example

Tell us what’s happening:
I actually got the question correct, but I wanted to understand how the array is involved in the recursive function. I understand that n is subtracted by 1 through each recursion until it reaches its base case but how exactly is the function adding the number from the array if it does not have a for loop to run through it?

Your code so far

function sum(arr, n) {
// Only change code below this line
  if (n <= 0) {
    return arr[0];
} else {
    return sum(arr, n - 1) + arr[n];

// Only change code above this line

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Challenge: Replace Loops using Recursion

Link to the challenge: