Var++ causes RangeError in recursive function parameter in JavaScript

Question

I have a simple linear recursive function in JavaScript computing a factorial of a number.

function factorialImproved(n) {

  function factorialIter(p, c, m) {
    if (c > m) {
      return p;
    } else {
      return factorialIter(c * p, c++, m); // RangeError: Maximum call stack size exceeded // ++c or c+1 is OK
    }
  }

  return (factorialIter(1, 1, n))
}

I'm trying to figure out why I get RangeError with c++ but not with ++c or c+1 .

Answer 1

(c++) evaluates as c . So you are calling factorialIter with the same c every time.

Therefore, c = 1 won't be bigger than m = n unless n < 1 .

However, (++c) evaluates as c+1 . Just remember this rule:

• (++c) : first increment then c .
• (c++) : first c then increment.

In my opinion, you should be using c+1 . Do not use c++ or ++c unless you want to use c in that scope later.

Answer 2

You return the same value of c , because with postfix increment , it returns the actual value and then it increments the variable.

For getting a result, you could use just c + 1 as value. Or use prefix increment. But if you do not use the variable again, it is not advisable.

 function factorialImproved(n) { function factorialIter(p, c, m) { if (c > m) { return p; } else { return factorialIter(c * p, c + 1, m); // RangeError: Maximum call stack size exceeded // ++c or c+1 is OK } } return (factorialIter(1, 1, n)) } console.log(factorialImproved(5));