primeFactors.js

/* (**) Determine the prime factors of a given positive integer.
 *      Construct a flat list containing the prime factors in ascending order.
 *      Example:
 *      * (prime-factors 315)
 *      (3 3 5 7)
 */

function prime(n) {
  if (n < 2) 
    return false;

  var i = 2;

  while(i < n) {
    if (n % i == 0) 
      return false;

    i++;
  }

  return true
}

function primeFactors(n) {
  var numbers = [];

  for(var i = 2; i < n; i++)
    if (n % i == 0 && prime(i)) 
      numbers.push(i);

  return numbers;
}