fibonacci.js

"use strict";

for (let i of fib(10)) {
  console.log(i);
}

function* fib(num) {
  let [prev, curr] = [0, 1];
  
  for (let i = 0; i < num; ++i) {
    [prev, curr] = [curr, prev + curr];
    yield curr;
  }
}