How does using a return clause before a recursive function call differ from not using one?

Question

I was just experimenting with some recursion and noticed something that confused me. Let me illustrate with some code examples:

function loop(x) {
  if (x >=          


        

Answer 1

If x<10 the loop function doesn't return any value, that' why return loop(x + 1); gives you "undefined". As soon as you reach 10, the return x; statement kicks off and you get your returned value.

The fact that you use it as a recursive function doesn't make any difference here.