Basic JavaScript - Replace Loops using Recursion

Tell us what’s happening:
Describe your issue in detail here.

Your code so far

i don’t understand the recursion part. please help me understand.

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

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Challenge: Basic JavaScript - Replace Loops using Recursion

Link to the challenge:

What exactly do you think this is referencing?

n is number, so n[1] does not make any sense here. n[1] is undefined, so arr[undefined] is going to be undefined.