const fibCallback = (count = 0, callback) => {
  let f0 = 0, f1 = 1, f;

  for (let i = 0; i < count; i++) {
    f = f0 + f1;
    callback(f0 + ' + ' + f1 + ' = ' + f);
    f0 = f1;
    f1 = f;
  }
}

function* fibGenerator() {
  let f0 = 0, f1 = 1, f = 0;

  while(true) {
    f = f0 + f1;
    yield f0 + ' + ' + f1 + ' = ' + f;
    f0 = f1;
    f1 = f;
  }
}

const fibIterable = {
  count: Infinity,

  *[Symbol.iterator]() {
    let f0 = 0, f1 = 1, f = 0, i = 0;

    while(f < Infinity && i < count) {
      f = f0 + f1;
      yield f0 + ' + ' + f1 + ' = ' + f;
      f0 = f1;
      f1 = f;
      i++;
    }
  }
}

const count = 20;

console.log('Fibonacci Series with arrow function with callback');
fibCallback(count, s => console.log(s));
console.log(''); // New Line

console.log('Fibonacci Series with generator function and yield');
const fibGen = fibGenerator();
for (let i = 0; i < count; i++) {
  console.log(fibGen.next().value);
}
console.log(''); // New Line

console.log('Fibonacci Series with iterable object and iterator');
fibIterable.count = count;
for (let value of fibIterable) {
  console.log(value);
}