The JavaScript Event Loop (Revisited): A Comedic Dive into the Microtask Madness 🤯

Oh, the JavaScript Event Loop — that mysterious heartbeat that keeps our asynchronous code ticking. We’ve already explored its basic workings, but now it’s time to dive a little deeper into the rabbit hole. 🕳️ Brace yourselves, folks, because things are about to get real (and real silly) as we uncover the advanced secrets of the Event Loop.

Let’s start with the Microtask Queue. 📋 These little buggers are like the VIPs of the Event Loop — they’re the ones who always get to cut to the front of the line, no matter how long it is. Imagine a group of rowdy partygoers, elbowing their way through the crowd to get to the front of the dance floor. That’s the Microtask Queue in a nutshell. 💃

console.log('Start');

Promise.resolve('Promise Value').then(function(value) {
  console.log(value);
});

queueMicrotask(function() {
  console.log('Microtask Callback');
});

console.log('End');

//OUTPUT

Start
End
Promise Value
Microtask Callback

See what I mean? The Microtask Queue just barges in, disrupting the natural flow of the Event Loop. It’s like that annoying kid in class who always raises their hand and blurts out the answer before anyone else can even think. 🙋‍♂️

But wait, there’s more! Let’s throw another player into the mix — the Job Queue. 🤹‍♀️ These are the “special VIPs” of the Event Loop, even more important than the Microtask Queue. They get to jump the line and execute before anything else, including the Microtask Queue. It’s like the teacher’s pet who not only gets to cut in front of everyone, but also gets extra credit for their efforts.

console.log('Start');

Promise.resolve('Promise Value').then(function(value) {
  console.log(value);
  queueMicrotask(function() {
    console.log('Microtask Callback');
  });
});

queueMicrotask(function() {
  console.log('Second Microtask Callback');
});

setTimeout(function() {
  console.log('Timeout Callback');
}, 0);

console.log('End');

//OUTPUT

Start
End
Promise Value
Second Microtask Callback
Microtask Callback
Timeout Callback

See how the Job Queue from the Promise resolution takes precedence over the regular Microtask Queue items? It’s like the school’s star athlete getting a free pass to the front of the lunch line, while the rest of us poor saps have to wait our turn. 🤴

But don’t worry, the Event Loop isn’t just a heartless dictator. It does have a method to its madness. 🧠 By understanding the priorities and the order of execution, you can learn to harness the power of the Microtask and Job Queues to write more efficient and predictable code.

So, the next time you find yourself scratching your head over some mysterious Event Loop behavior, remember: it’s just a chaotic dance of priorities and queues, with a few VIPs thrown in for good measure. 💃 Embrace the madness, learn the steps, and you’ll be waltzing through your JavaScript code like a pro in no time.

Happy coding, my friends! May the Event Loop be ever in your favor. 🤞

“For a more Joyful explanation, continue reading our blog post ‘When JavaScript Met the Event Loop: A Comedic Romance of Synchronous and Asynchronous Love’ ”

https://medium.com/@nikhilnikki747/when-javascript-met-the-event-loop-a-comedic-romance-of-synchronous-and-asynchronous-love-38097daa26cf