[removed] recursive function returns undefined for existing value

Question

I am trying to loop an array using a recursive function. The loop should stop and return the value of the key, if it matches a given regex pattern.

The loop stop

Answer 1

You have to return the value from the recursive call,

  // recall with updated index
  return loop(arr,i); 
}

The final call for the function loop will return a value, but the other calls for the same function returns undefined. So finally you end up in getting undefined