Iterator.prototype.filter()

filter(callbackFn)

function* fibonacci() {
  let current = 1;
  let next = 1;
  while (true) {
    yield current;
    [current, next] = [next, current + next];
  }
}

const seq = fibonacci().filter((x) => x % 2 === 0);
console.log(seq.next().value); // 2
console.log(seq.next().value); // 8
console.log(seq.next().value); // 34

for (const n of fibonacci().filter((x) => x % 2 === 0)) {
  console.log(n);
  if (n > 30) {
    break;
  }
}

// Logs:
// 2
// 8
// 34

for (const n of fibonacci()) {
  if (n % 2 !== 0) {
    continue;
  }
  console.log(n);
  if (n > 30) {
    break;
  }
}