microtasks-example.js

console.log("first");

// enqueue a Task after this Task
setTimeout(function() {
  console.log("fourth");
}, 0);

// enqueue a microtask within this Task
Promise.resolve()
  // enqueue a microtask after this microtask
  .then(function() {
    console.log("second");
  })
  // enqueue a microtask after this microtask
  .then(function() {
    console.log("third");
  });

// output: 'first' 'second' 'third' 'fourth'