https://www.jsv9000.app/ - event loop examples

What is queueMicrotask()?

queueMicrotask() lets you schedule a function to run at the end of the current call stack, before any macrotasks like setTimeout. It adds the function to the microtask queue, just like .then() from a resolved Promise.

queueMicrotask(() => {
  console.log('This runs after the current call stack, but before setTimeout');
});

✅ Goes into the microtask queue:

• Promise.then(...)
• Promise.catch(...)
• Promise.finally(...)
• queueMicrotask(...)
• MutationObserver callbacks

✅ Goes into the macrotask queue:

• setTimeout(...)
• setInterval(...)
• setImmediate(...) (Node.js only)
• fetch(...).then(...) → the .then() goes here after the network completes
• DOM events (e.g., click, input)
• I/O operations (like reading a file, network responses, etc.)
• requestAnimationFrame(...) (sort of its own phase — executes before repaints)