sum of even numbers in Fibonacci sequence

Question

I\'m trying to create a function to calculate the sum of only even numbers in Fibonacci sequence. How can I make this if/while loop to work?.

function fib() {
         


        

Answer 1

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

  for (let i = 0; i < num - 2; i++) {
    let c = a;

    a += b;
    b = c;

    if (a % 2 === 0) {
      acc += a;
    }
  }

  return acc;
}

console.log(sumFibs(10)); // Logs out the even sum of the first 10 fabonacci sequence