Simple Recursive Javascript Function Returns Undefined

Question

For an assignment I am supposed to write a recursive function that checks any integer for even or odd using N-2. If even returns true else returns false. But it returns undefine

Answer 1

You have forgotten the return statement before the recursive isEven(num) call.

See the snippet below:

function isEven(num) {
  //console.log("top of function num = " + num);// For Debugging
  if (num == 0){
      return true;
  }
  else if (num == 1){
      return false;
  }
  else {
    num -= 2;
    return isEven(num);
  }
}
console.log('0 is even: ', isEven(0));
// → true
console.log('1 is even: ', isEven(1));
// → false
console.log('8 is even: ', isEven(8));

Answer 2

You can change the following line:

isEven(num);

to

return isEven(num);