generators

function* simpleGenerator() {
  console.log("First execution");
  yield 1;
  console.log("Second execution");
  yield 2;
  console.log("Third execution");
}

const gen = simpleGenerator();

console.log(gen.next()); // { value: 1, done: false }
console.log(gen.next()); // { value: 2, done: false }
console.log(gen.next()); // { value: undefined, done: true }


function* infiniteSequence() {
  let i = 0;
  while (true) {
    yield i++;
  }
}

const seq = infiniteSequence();
console.log(seq.next().value); // 0
console.log(seq.next().value); // 1
console.log(seq.next().value); // 2


function* asyncFlow() {
  const data = yield fetchDataFromAPI();
  console.log(data);
}

const iterator = asyncFlow();

iterator.next().value.then((data) => {
  iterator.next(data);
});


function* stateMachine() {
  while (true) {
    const state = yield;
    switch (state) {
      case "START":
        console.log("Starting");
        break;
      case "PAUSE":
        console.log("Pausing");
        break;
      case "STOP":
        console.log("Stopping");
        return;
    }
  }
}

const machine = stateMachine();
machine.next(); // Initialize the generator
machine.next("START"); // Starting
machine.next("PAUSE"); // Pausing
machine.next("STOP"); // Stopping


function* typedGenerator(): Generator<number, void, unknown> {
  yield 1;
  yield 2;
  yield 3;
}