sum-all-odd-fibonacci-numbers.js

// Sum All Odd Fibonacci Numbers

/*
Given a positive integer num, return the sum of all odd Fibonacci numbers that are less than or equal to num.

The first two numbers in the Fibonacci sequence are 1 and 1. Every additional number in the sequence is the sum of the two previous numbers. The first six numbers of the Fibonacci sequence are 1, 1, 2, 3, 5 and 8.

For example, sumFibs(10) should return 10 because all odd Fibonacci numbers less than or equal to 10 are 1, 1, 3, and 5.
*/

function sumFibs(num) {
  let a = 0;
  let b = 1;
  let sum = 0;

  while (b <= num) {

    if (b % 2 !== 0) {
      sum += b;
    }
    b += a;
    a = b - a;
  }
  return sum;
}

sumFibs(4);