Javascript Factorize 返回不正确的结果

Question

Just wondering if anyone can tell me why this returns 100 and not 120? It should calculate the total number of the factor.

function factorialize(num) {

  for(var i = 1; i <= num; i++ ) {
    var fact = i+i;    
    total = fact * fact;
  }
  return total;
}

factorialize(5);

Answer 1

This is not the correct way to calculate the factorial. What is happening in your code is, the last time the line total = fact * fact; is run, fact has a value of 10 (because i is 5), so 10 * 10 becomes 100 and that is what it returns.

Answer 2

TLDR is you're overwriting all the values of fact . var is scoped to a function in JS. Eventually you reach i = 5 , which eventually sets fact to (5+5) * (5+5) which is 100.

Answer 3

If you are trying to calculate the factorial, use this code:

function factorialize(num) {
  var total = 1; // Initialize the total. 0! = 1.
  for(var i = 1; i <= num; i++ ) {

    total = total * i; // Add the current index to the factors by multiplying it by the current total.
  }
  return total;
}