yield-test.js

function* testYield() {
  console.log("#1");
  
  yield new Promise(r => setTimeout(r, 2000));
  console.log("#2");

  yield new Promise(r => setTimeout(r, 2000));
  console.log("#3");
  
  return;
}

function* spawnTest() {
  yield testYield();
  console.log("#4");
}