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✨♻️ JavaScript Visualized: Event Loop

Lydia Hallie on November 20, 2019

If you're here in 2024 (or later), here's an updated blog post!](https://lydiahallie.com/blog/event-loop) Oh boi the event loop. It’s one o...

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Logan • Nov 22 '19

Hi, Lydia Hallie, it is a great article.

Can I translate this article into Chinese to help more Chinese developers(With original author and link, of course).

Lydia Hallie • Nov 22 '19

Absolutely!

Comment deleted

Diego Palacios Lepore • Mar 4 '20

Hi, Lydia!

This is such a great article! 😃

I was looking a clear post about this subject and yours is super comprehensive and well explained (btw, I loved the gifs). I'm planning to talk to my team about the event loop soon (in spanish).

I'm sure you might have heard about this tool that helps you play with this cycle and see in real time how it goes:

latentflip.com/loupe

Shelby Anne • Sep 1 '22

woah that tool is awesome!

Muhammad Ayaz • Dec 9 '22

The tool is amazing, if we have 2 aysnc functions, the web api section will only show the latest one

Sherlock • Mar 25 '23

Amazing tooling！！！

Miodrag Dzamic • Mar 2

I tried to copy paste some code into tool and it does not save after clicking Save+Run button. Does someone else has same issue? Thanks!

Eugene Karataev • Nov 22 '19

Thanks for the great article and animations!
It's interesting why "event loop" question is so common on interviews, if it's job is just to transport code blocks from the queue to the call stack. I think better question would be to ask to describe how the JS mechanism works as a whole thing with call stack, web api, queue and event loop.

Rafael Beckel • Nov 20 '19

Interesting article! What did you use to animate the gifs?

Lydia Hallie • Nov 20 '19

As a true professional I use keynote and screen record it lol

squidbe • Nov 25 '19

Professional enough!

thebilson • Nov 21 '19

I'm also a visual learner, so this was very helpful. I'm still early on with JavaScript and it's challenging to understand it all; are there any books out there for us visual learner that you might recommend?

Anoop Sivadas • Nov 24 '19

Try the book written by a John duckett

Oscar Calderon • Nov 29 '19

Hi Lydia. Thanks for taking the time of generating these animations in order to explain it in a very simple way. Still, I have doubts regarding the Call Stack. Is it the same as the main thread in which JS runs? I mean, I understood that, although JS is single threaded, but for the asynchronous logic that gets executed, NodeJS would spawn threads for it while processing the main logic in the single thread. Thanks in advance :)

Manav Misra • Mar 10 '20

This is a great ❓, but probably gets a bit more 'low-level' than we need to just understand the behavior of our JS code with relation to the event loop.
However, my understanding is that the JS Engine/Runtime Environment consists of only the stack and the heap. The stack is what is 🏃🏽‍♂️on that single thread. Meanwhile, that message queue is part of the asynchronous browser environment. So, JS's single thread runs through call stack on its single thread and then checks that mesage queue to see what else needs to be done on its thread when it has the chance.

avneeshroks • Dec 19 '20

I think in case of NodeJs, it's just the c++ Api's Insted of web/browser's Api.

SebasQuiroga • Dec 3 '21

Hi @avneeshroks , I have recently cloned and run the NodeJS code and effectively C/C++ are dominant.
Remember that NodeJS is on top of the V8 engine (the one used in the Chrome browser) that Google opensourced and it is natively written in C++, running in the browser and running in a server are two different environments with different purposes and indeed different APIs. NodeJS is literally running on the same engine than Chrome, but for NodeJS it is not needed to have APIs such as those for the DOM, Window, etc as Chrome needs.

Jude • Nov 27 '19

I'm not a JS developer but every now and then I have to dig into it. Over the past few years I've read lots of random things about the event loop but this is the first time I've had a clear picture of what's going on in the web browser (via the web api). Thanks!

Rogério Munhoz (Roz) • Feb 25 '20

Awesome article! This has helped me a lot!

I was thinking about translating this series into Brazillian Portuguese. Do you happen to know if anyone has done it yet? Would you mind me doing it (ofc with links to the original series)

João Paulo • Oct 1 '21

I had the same ideia. I really want to share with the team i'm part of so did you translate it or not? You found someone that did the translation of this article?

Syed Mustafa Naqvi • Jan 26 '22

Hi, Lydia Hallie can you tell me what is the case with setInterval in call stack a combination of setTimeout and setInterval see the usecase below. Is setInterval also supposed to go to webAPI?



let c = 0;
let id = setInterval(()=> {
console.log(c++)
},200)

setTimeout(()=> {
clearInterval(id)
},2000)
// prints
/* 0
1
2
3
4
5
6
7
8 
9
and then stops  */

Maksim Rozhkov • Feb 15 '23 • Edited

2000/200 = 10 times

after 2 seconds we clear setInterval id

Jonas Røssum • Nov 23 '19

Really nice article!
One thing I was confused about was

invoke bar. bar returns a setTimeout function.

Doesn't setTimeout return an id that you can pass to clearTimeout? 🤔

Ibrahim Joseph M. • Nov 26 '19

Yes, It does Jonas, so lets say


let id = setTimeout( () => {
return "hey"}, 1000);

console.log(id) // you will get 1

let id2 = setTimeout( () => {
return "hey"}, 1000);

console.log(id2) // you will get 2

thamer belfkih • Feb 2 '20

thank guys to point out this detail, in the same context what's the purpose of this Id and it is used by the web API or the call stack for some purpose? thanks in advance

Leandro Rodrigues • Nov 25 '19

Great article Lydia.
Thanks so much for bring that clear explanation.

Karim Muhammad • Aug 14 '22 • Edited

I have question here...

function hello() { // sync
console.log("hello");
}
function afterWhile() { async
  setTimeout(()=> {
    console.log("After Timer")
  }, 0)
}
afterWhile();

hello();  // gets added in callstack then pop it out sequentally;
// so callstack is empty here, i guess?!!!! so why callback hasn't been executed here, in this time

hello();

callstack here carry on one task then remove it, so why callback hasn't executed after popping out instanctly?

Jeannot MN • Sep 13 '22

Functions are pushed into the the call stack when the callstack is empty AND there are no other line of code to be executed in the main thread... in your case it was not pushed because there was still one more thing to execute in the main thread of execution (the second hello()); Only after completing the second call to the hello function that your callback will be pushed into the callstack...

I hope this helps.

Nick Chen • Jun 10 '21

Hi Lydia, I love the series. Just wondering what tool did you use to make those animations? I'm also writing some tech stuff but I can't find a perfect virtualization tool to illustrate my ideas, but your animations really match what I was looking for.

Stanley Sathler • Nov 21 '19

Thank you so much for the illustrations, Lydia! Very helpful, indeed!

One question: what happens when the main thread is blocked - i.e. the UI freezes? Would the whole interaction within that viewport be blocked - e.g. cursor wouldn't change after hovering a link?

I think I've never faced this situation before, so I'm curious how to identify such situation. Is there any way to simulate a huge processing in order to freeze my UI, just to see that?

Thanks in advance!

bru • Jan 21 '20

Hi, you can try this:

        function wait5seconds() {
            const plus5seconds = new Date().getTime() + 5000;
            while ( plus5seconds > new Date().getTime() ) {}

            console.log( 'wait5seconds end' );
        }


        function clickHandler() {
            console.log( 'click event' );
        }

        document.addEventListener( 'click',
            clickHandler ); // al comunicarme con la API del DOM estoy saliendo de JS 

        wait5seconds();
        console.log( 'end script execution' );

Execute this script, and press a lot of clicks, the clicks events will appear at the end ( because the dom events are push into the queue.

I think that what you need to take into consideration is when you are performing a task that it might take some time, that might block the UI.

GaurangDhorda • Jan 28 '20

In this particular case de-bouncing is useful when we click on button..

Pankaj Kumar • Dec 14 '19

Just write a for loop which is printing millions numbers. Call this function on any click function. You will see the effect.

Johannes • Jan 2

Hi Lydia,

I'm refreshing my knowledge on the event loop and even though your article is mostly correct, it does not start strong with the incorrect statement:

The respond function returns a setTimeout function.

This is incorrect. The respond will return an integer. You can easily check this yourself by doing:

const returned = respond();
console.log(returned === parseInt(returned)) // true

aaktansel • May 21 '23

Hi Lydia ,

Thanks for this useful article explaning a difficult to understand concept in a very simple way. And i want to translate it to Turkish to share in my personal blog, with linking the original author, do you have permission for this?

Ramiro • May 12 '23

excelente articulo, pensar que hace unos meses no entendia nada pero guarde el articulo ya que sabia que esto era clave, y ahora de tanto repasar js vanilla, pude entender jeje saludos desde la Patagonia, argentina.

Eric Cornwell • May 17 '20

Great explanations and descriptions. Interesting to note that in the final example the timer value is unimportant. Someone who is unaware of how the queue works might be surprised to find that a timer value of 0 still logs "Second" last. Which is actually an easy way to yield to the UI during a long-running process if it can be continued via a timer callback, which will happen virtually immediately if the queue is empty.

Yejin • Jan 30 '20

Thanks for the great article, Lydia! Do you mind if I translate this JS Visualizeed series into Korean with the original article and author credit? I think a lot of Korean developers would be interested in learning them.

Vicent • Apr 6 '20

Bravo! It's a great article, exactly what I was looking for showing to my team.
Just an extra consideration, it would be very cool to show a final example when we have actually more than one async item at queue. Taking into consideration different times of response for those functions.

Chanmi Lee • Jun 7 '20

Tons of thanks for this great article and awesome animations! :)
I wonder if it would be possible to translate this article to Korean with the original post link for making this useful content be more accessible for other readers.

Omar Pervez • Aug 14 '22

It's great article I saw. I have no more confused about it. I was trying to learn it but I can't. but Thank God, That I got your article on my browser home page. I want to also thank you daily.dev. they saw your article on my home page and I have come to your article and learned about event loop. Again Thank you so much Lydia Hallie from Omar.

Rishav Kumar • Oct 5 '21

Hi, Lydia Hallie, this is a really informative article.
Please make a similar article on event loop in Node.js if possible.
It will be of immense importance to me as I am unable to get a proper explanation with an example.

Max (he/his) • Nov 20 '19

Good post, I really appreciate the effort you do to explain the things :)

Adnan Babakan (he/him) • Nov 25 '19

Hi Lydia
This an amazing visualization and demonstration of JavaScript event loop.

I want to ask you permission to translate this article to Persian (Iran's language) with the original post link of course so this article would be more accessible for other readers.

Lydia Hallie • Nov 26 '19

Sure 😃

oles-bolotniuk • Nov 28 '19

The best explanation I've ever seen, thank you for sharing!
What's the role of the HEAP that's mentioned on the first picture?

Songfeng Li（李松峰） • Feb 5 '20 • Edited

Good demonstration! But a little issue exists in my opinion.

The 1st animation, when the respond() function was pushed to the call stack and executed, the setTimeout() function should be pushed into the call stack (and executed) as soon as possible, instead of waited for about 1 second. Because, as the first and only one line code inside the respond() function, the call to setTimeout( ) should be executed immediately at that time. The second argument of setTimeout(), 1000ms, has only to do with how long the timer should be waiting to add the callback to the task queue, it does not have any effect for when the setTimeout() should be pushed into the call stack.

I wish I had made this little issue clear. btw, the last animation has the same issue too. Thank you.

avneeshroks • Dec 19 '20

Hey Lydia! This was amazingly explained! One thing I'm still now able to understand is what's microtasks and macrotasks! How engine prioritize those? Also how the Render/Paint queue work with the Normal queue?

Samuel Henshaw • Apr 15 '20

I was, currently and still impressed and wowwwwwed by this article. its as if this is the first time i am seeing a Promise.

Great article

DevWorksSimone • Nov 21 '19

I love gifs! Thanks for explanatio ! Not programming in javascript but was very interesting ti read!

Gabrielduerto • Apr 6

Muchas Gracias Lydia, aunque no pude entender tu video, el texto esta bien explicado y pude traducirlo, se que tengo que aprender Ingles, tan pronto termine el bootcamp hare un curso intensivo de Ingles, igualmente muchas Gracias por tu Articulo <3

Vanessa Osuka • Nov 21 '19

So it's safe to say the purpose of the event loop is to prevent any callback clashes? 🤔

Lydia Hallie • Nov 21 '19

Hm no, not really. Imagine we have 4 tasks, and the 2nd tasks needs a delay. If this delay would've happened on the main thread, nothing would've been able to run on the thread while we were waiting:

However, the web api gives us some sort of asynchronous behavior by letting us put stuff "to the side" so to say. We can now keep on running other tasks, thus keeping an interactive UI, while tasks are running in the background:

Hope this somehow made sense haha I just woke up so my illustrations may not be optimal 😜

Stanley Sathler • Nov 21 '19

So can we say that preventing callback clashes is the queue's job, instead of event loop's one?

DevWorksSimone • Nov 21 '19 • Edited

Great!

Jeannot MN • Jul 28 '22

Thanks for the detailed post😃.

I have a question regarding this "Luckily, the browser gives us some features that the JavaScript engine itself doesn’t provide: a Web API. This includes the DOM API, setTimeout, HTTP requests, and so on. This can help us create some async, non-blocking behavior 🚀"

Does the Web API allow us to create asynchronous behavior? Doesn't it just give us features that the JS Engine does not have?
Am I wrong saying it's rather the event loop and the callback queue that allow us to create asynchronous behavior?

Lars • Nov 25 '19

Awesome, thanks

Deyvison Rocha • Nov 26 '19

Nice article! Thanks for share!

MOHAMED ZABOUB • Oct 23 '21

I just wanna thank you for this amazing explanation, the first time I've read this 3 months ago, everything was new to me and blur.

Today I went on it again and it's just crystal clear too!

Thank you 3

Gonzalo • May 16 '21

Amazing!, it was so helpful, thanks

侃小溪 • Jun 3 '21

Hi, Lydia Hallie, Thank you for your great work. I want to translate your articles in Chinese to improve my English and skills😊.

A5h1m • Jun 6 '21

Fantastic visualization. Thanks Lydia

Aleksandr N. Ryzhov • Nov 26 '19

Thanks!

Evelyn Pei • Sep 18 '20

Very helpful in further understanding the event loop! Thanks for posting, Lydia! :)

STARK • Aug 17 '23

I just can't believe how ellaborate and simple this blog is !!!.This seriously made my day and saved me a lot of time.kudos to the writer!! I specifically created an account to make this comment to support this author.Expecting a lot of concepts to be simplified with gif's.

thanhtrung • Feb 3 '23

The timer runs, in the meantime foo gets invoked and logs First. foo returns (undefined),baz gets invoked, and the callback gets added to the queue.

I don't understand why it can log undefined in here, can you pls explain more ?

Maksim Rozhkov • Feb 15 '23

this functions return nothing

bigleegeek1 • Nov 25 '19

As a newbie to learning JS I appreciate your post and look forward to others.

bigleegeek

Abinash Panda • Nov 26 '19

what about microtasks?

Markus Seyfferth • Nov 26 '19

Hi Lydia,

such as great and helpful article! Would it be OK with you to translate it into German and to republish it on drweb.de/ (with your author bio, of course)?

Thank you, — Markus

Lydia Hallie • Nov 26 '19

Absolutely!

Markus Seyfferth • Nov 26 '19

Thanks so much!

Douglas Fugazi • Nov 25 '19

Super nice explanation. I've learnt new things with this article. Thanks!

Elango Sundar • Nov 21 '19

Nice awesome articles and visullay explained the event loops :)

Carlos Trapet • Nov 20 '19

Good stuff, Lydia! You have a very nice and straight-to-the-point way of expressing concepts, I'd love to read some more posts of yours, if you do have any!

Lydia Hallie • Nov 20 '19

Will post them soon 😎

Dayvster 🌊 • Nov 20 '19

You did a fantastic job of explaining and animating this.

hannad rehman • Feb 1 '20

What if there are no functions is the program?.lets say i have 10 instructions like variable deceleration, assignment , arthematic operations etc. Will all these instructions also go to call stack?
Var a = 10:
Var b;
b = a+ 10;

Jeannot MN • Sep 13 '22

These will be executed in the global execution context... which is at the bottom of your call stack

Rodolpho Bravo • Apr 21 '20

Hey, Lydia! How have you been? Awesome article!!

Can I translate this article series into Portuguese? (With original author and link, of course).

Diana Lozano • Apr 28 '23

Looks like "What the heck is the event loop anyway?" by Philip Roberts | JSConf EU
https://www.youtube.com/watch?v=8aGhZQkoFbQ&vl=en

Gizela Delgado Soto • Apr 8

This is really usuful, the graphics help a lot 🤗

asuna24 • Feb 23

Hi @lydiahallie , thank you for your super comprehensive explanation. All of the gifs are incredible, helped me a lot to understand more about javascript under the hood.

Soe Moe Htet • Jan 16 '23

Thanks for a great article series. 👍

DangNguyen • Oct 5 '23

Amazing, really like you visualization

Pratap Sharma • Aug 13 '23

Hi @lydiahallie It was an amazing article and animations.

How did you create those animations?

Chidera Humphrey • Jun 27 '23

Super helpful and well written.

Thanks for taking your time to share this with us.

Hieu Nghia • Jun 22 '23

nice****

Doston • Jun 4 '23 • Edited

Hello , Lydia Hallie, it is a great article.

Can I translate this article into Uzbek to help more Uzbek developers(With original author and link, of course). too

Jatin Kumar • Apr 15 '23 • Edited

Very informative. Hats off to the explanation!!!

zhangbowy • Mar 21 '23

Can I translate your article to a Chinese technical website? , will comment the original link

kazinoman • Feb 25 '23 • Edited

Tnx for your effort.

Prafulla Raichurkar • Jan 25 '23

Wow, nicely explained :D

Tamb • Jan 19 '23

You explained this beautifully! Thank you!

Fernando Rodrigues • Nov 30 '22

I love it! I’m a visual learner too so this helps a lot! Keep going! o/

NovaJay2415 • Nov 22 '22

Super helpful! I love this!

Tu Nguyen • Nov 21 '22

It is a very visual and great, easy to understand, you saved my life.
Hungry to read these kind of posts.

Love your post!!!!

capscode • Sep 21 '22

Wow...
Amazing article for and amazing topic of JS by an amazing writer with an amazing explanation.

thanks for sharing this.

ehza • Aug 20 '22

This is fantastic!

Robson Muniz • Aug 19 '22

Wow, Great Contet, thanks for sharing it!

mohmmadmoussa1988 • Aug 16 '22

Great Visuals, Thank you

Upasana Mahanta • Aug 14 '22

Great article and animations!

Sachintha Dhananjana • Aug 14 '22

This is a Great job.It makes really easy to understand the concept.

crazy4groovy • Aug 13 '22

Thanks!

Now it time to add the promise's micro queue! :)

Darshit Gajjar • Aug 13 '22

Great Article Lydia, make this kind of Articles ❤️

Jeff Chavez • Aug 13 '22

Wow. This is so helpful since JS is really challenging. Thanks for the effort.

Monish Soni • Apr 25 '22

Thank You so Much !!

Esteban Vera • Feb 22 '22

Hi, Lydia!
You are the best!

islam saeed • Feb 1 '22

👍 the best one explained event loop ➿

i love Math • Nov 18 '21

hi Lydia
you mentioned "web API" so what do you mean "web API"? I don't understand what is "web API" , which you are referring to?

i love Math • Nov 18 '21

Hi, Lydia Hallie
you mentioned "web API" so what do you mean "web API"? I don't understand what "web API" is, which you are referring to?

Vikas Chauhan • Oct 6 '21

This is the best article on event loop I have encounter so far.
Thank you so much for making it so wasy for us :-)

MarkAndersonNC • May 5 '21

Great article. JS is so hard to learn

ajay08-code • Apr 28 '21

Gifs are so explicit. You really explained everything perfectly

Anish Agarwal • Apr 13 '21

Glad to find such a gem !

Francesca T • Apr 9 '21

Thanks a lot Lydia!

Cagatay Unal • Mar 31 '21

Thanks for the great article.

Nate Spring • Jan 5 '21

The visualization helps so much! Thank you very much for putting the time into this.

rhaegar453 • Sep 22 '20

This is one of the best articles I've seen on Event Loop. Thanks, Lydia for sharing :)

Agha Azeem • Nov 27 '19

Fantastic 👍

martin jose • Jan 6 '20

And finally i started to understand how the event loop works, thanks a loooot. I've been reading for days feeling confusing. Great job with those gif, love it.

Sudharsanan Ravichandran • Jul 6 '20

This is a great article, thanks for sharing!

Prince Buchi • May 1 '20

Wow

cucheng • Apr 26 '20

Nice, thank for you...love you <3

perpetual . education • Dec 5 '19

Great job! Here's a deep dive from another presenter: latentflip.com/loupe - and with a live app to show the visualizations.

Rodrigo Schneider • Jan 20 '20

Thanks for this article and also the others. Awesome explanation and awesome GIFs! Cool idea. I hope you have a nice day! :)

Vandstein • Apr 30 '20

Thank you for sharing, it's really interesting!

NhutHuynh • Jan 18 '20

Great article, amazing animations makes me understand the topic easily.

Gislene Carvalho • Jan 22 '20

It's a gift of the Gods for a visual learner like me. Thanks for this ultra helpful article.

Aidas Bendoraitis • Jan 27 '20

These series are such a pearl. Thanks for creating them. I am very happy to have found them.

Karthikeyan A. • May 1 '20

Hey Lydia, what about event listeners/callbacks? How do they work internally?

Sutthinart Khunvadhana • Dec 3 '19

Fantastic article. Love the way you explain things step-by-step.

Kus Cámara • Dec 23 '19

Great post! Worths mentioning the job or microtask queue (promises) that has higher priority than the callback queue.

jameslam • Mar 26 '20

Great article, thanks! Could you please explain macro task and micro task in this visual way? It can definitely help others！

Átila Camurça Alves • Jan 10 '20

Great article!

Have you heard of loupe? latentflip.com/loupe/

Sarah Chima • Jan 23 '20

Super clear explanation. Thanks for sharing this.

Mustafa Ensar • Feb 21 '20

Hi Lydia Hallie,

I'm gonna make a presentasion and tell this subject to other students like me in my class. Can I use your gif images :)

Sriram Sharma • Jan 31 '20

Lydia, thank you for breaking this down for us! As a visual learner, this is gold!

Julio Saraiva • Apr 10 '20

Awesome. Great Job!

JinYoung-Lee • Jan 27 '20

Super nice article. Thank you for writing the post😊

I want to translate this post series into Korean. May I do this leaving the link and original author?

Yaman Agrawal • Mar 29 '20

Lydia, big thanks, I have been coding for a while now, always wished I had some visual guidance at the start of my career and here you are. BIG THANKS AND HUGE RESPECT.

Francesco Di Donato • Feb 12 '20

Hello Lydia,
I really appreciate you piece of work. Congratulations.

Paras 🧙‍♂️ • Apr 16 '20

good good good...these visualizations are fabulous !!

Daeun Kang • May 13 '20

Hi, thank you for great article.
Can I translate this series into Korean in my blog? (of course with original author & link)

diepvv • May 5 '20

Hi, Lydia, it is a great article.

Oussama • Feb 25

very insightful thank you

Ester Kaufman • Jan 12 '23

Hi, Lydia, i think this is the best post to get the JS loop behind the scenes.

Can I translate this post, and publish it on my blog, with credits to the author and direct link?
Thanks for posting!

Khiêm • Feb 13 '23

Awesome!

Jongeun Kim • Dec 31 '20

Hi, Lydia.
Your article was of great help in understanding javascript.

Could I upload your article in Korean translation?
It would greatly help other Korean developers !!

EN • Dec 10 '20

Great Series! Love them, what did you use to create your animations?

Renato Francia Castillo • Feb 18 '20

This is so COOL! What did you used in order to do the animations?

kuldeep patel • Jan 1 '21

I really love this article...
My mind is blown. 🤯
😅
This article is very used fully for me. Thank you Lydia Hallie. 🙂

Kiran Kamath • Jun 30 '21

Why does event loop makes sure the call stack is empty , if there is already a callback function inside queue waiting to be invoked?

El-amiir • Feb 14 '23

Great article, Thanks.

JeongwonKim • Jan 16 '20

Hi.
This is interesting article!!!
So, i want translate Korean.....
Is it possible?

Trần Đức Hòa • Feb 28 '23

Great article! Thanks.

SebasQuiroga • Dec 3 '21

Great article Lydia!

Bilal Niaz • Jan 28 '22

Hi, Lydia Hallie, it's good article

Anil Loutombam • May 7 '20

The GIF you put just, make my things so loud and clear, thank you so much.

ᴏɴᴇꜱ ᴅɪᴏᴜᴀɴɪ • Mar 7 '23

Great article
Thanks Lydia

Rash Edmund Jr • Apr 8 '23

thanks @lydiahallie

Karthikeyan A. • May 1 '20

Lydia, what about event callbacks like click, scroll. How do they work?

PRAJWAL PATIL • Nov 15 '23

Nicely explained.. thank you so much

Kamila Santos Oliveira • Jul 23 '20

awesome content!

khaled-alwakel • Jul 17 '22

thank you so much . it was very helping ..

Hagay Haut • Aug 15 '22

Thanks for putting these together! I've been reading about some of this stuff and this really helps it click.

Marina • Nov 27 '19

Thanks a lot! It doesn't look scary anymore

Devidmaul • Apr 22

Still learning Java. It's little bit difficult for me. I used it on my project Infinite Craft

Abdallah Samir • Aug 17 '22

please i need to know how it works with more than async operation
such as 2 of setInterval or 2 of setTimeout

Thank you

Ramy Al-Sabry • Sep 29 '22

Hi, Lydia Hallie, it is a great article.
Thanks so much, finally i understand it.

EdgarMC100 • Dec 14 '22

This article helped me to remember what I read in a book in just 5 minutes, thanks Lydia. I consider myself a visual learner.

Don Jude Joseph • Dec 26 '22

Thank you Lydia Hallie fo this article

Hossam Omar • Aug 2 '20

great article, thank you very much

Maysam • Mar 26

wow!