JavaScript Visualized - Event Loop, Web APIs, (Micro)task Queue
Вставка
- Опубліковано 23 тра 2024
- Learn how the browser event loop, task queue, microtask queue, and Web APIs work together to enable non-blocking, asynchronous JavaScript.
- / lydiahallie
- buymeacoffee.com/lydiahallie
- / lydiahallie
- / lydia-hallie
- / theavocoder
Timestamps:
0:00 Intro
0:32 Call Stack
1:18 Single-threaded Problem
2:01 Web APIs
2:47 Callback-based APIs
4:04 Task Queue
4:39 setTimeout
6:22 Microtask Queue
8:40 Promisifying Callbacks
8:57 Challenge
10:52 Recap
11:58 Outro
Btw if you're in a hurry you can just fast-forward to 10:52 haha! I use Apple Keynote for everything.
💡Just a heads up: I explain these concepts in a way that personally helped me conceptualize the processing order.
E.g. the event loop doesn't directly "prioritize" the microtask queue, rather they're just processed and completed before the event loop continues to the next task. One iteration of the event loop is executing a single task, processing all available microtasks, and then updating the rendering of the page if needed (that's not covered in this video, might be another video, things like requestAnimationFrame). However, within your code, you'll get the sense that the microtasks are "prioritized" over the task queue-based parts.
Gotta love you for respecting our time.
From where did you learn?
Can you please extend this more to explain NodeJS runtime 🙏
Those slides are wonderful, it’s still a mystery to me how they are so good. Skills.
Thank you for doing this. I love the visuals you made here!
i think thousands of senior developers finally understood it today.
🤯
fake senior developers. No theory , not a real dev!
Knowing the todays reality, you wanted to say "junior" developers ? : )
@@KAIDO-mi1tr haha
now adays, senior and junior have similar salary, so whats the difference
Where has this channel been all my life?
Exactly I was thinking the same 😂
In the future obviously. 😂
She already done a longer vid for freeCodeCamp 2 years ago and she's on FrontedMasters as Teacher
ua-cam.com/video/xckH5s3UuX4/v-deo.html
Same here❤❤❤❤❤
Exactly!!
I have been programming for 15 years and I don't think I have seen information presented so succinctly in that span. Thank you so much for this.
100%
Absolutely 🤟
This video should receive the Oscar for best animation
If anyone had a question in the Challenge section as to why console.log(1) didn't execute immediately, even though it was in the Microtask Queue and the Call Stack was empty, read on.
All the code on the left is a script and can be represented as an anonymous function. At the very beginning of the "Challenge" section in the Call Stack, there should have been an "anonymous" block. This block starts executing (the script is being executed), and then everything is the same as in the video, except that the "anonymous" block is always at the bottom of the Call Stack. The "anonymous" block disappears from the Call Stack after console.log(5) is executed, because it is the last operation in the script.
And so when the "anonymous" block disappears from the Call Stack, Microtask Queue and Task Queue processing starts (10:04).
Great video!
Thank you. Absolutely wondered this.
I've been in software development for 16 years. This video is outstanding. Probably one of the best I've ever seen for JavaScript.
Lydia, I want to encourage you to keep doing these if you desire. This visual, animated approach combined with your ability to teach is a home run.
Thank you so much for doing this. I am now subscribed.
9 years ago was this video... her video seems a rip-off
ua-cam.com/video/8aGhZQkoFbQ/v-deo.html&ab_channel=JSConf
I can only agree. Especially for this topic, it was hard to find such an amazing explanation. You really helped me out. Thank you,
ditto
@Lydia Hallie Are you kidding? This level of detail, every animation, every transition, the highlighting (and temporarily hiding unimportant components) is just so good.
Very well done, love it.
One of the best video on event loop, till now on youtube, words are not enough to appreciate it... really... thank you...
it is very very rare to have material like this presented in such a visual and engaging way .. animation is hardly ever used in js tutorials. Visualization of these concepts is so important for the visual learners out there. THANK YOU.
instantly subscribed.
Okay ma'am, I noticed you only have 3 videos on your channel. Don't stop until you have at least a 20 video playlist on your channel. This is gold.
wow the visualization is awesome. The colours, gradients, design and animation. Its perfect down to the tiny details.
This video is way better than watching my favorite golden buzzer artist for the first time. Off the charts explanation. This video has just made history. Thank you so much. I had gone through a similar tutorial, yet, this one is so easy to follow.
This is the type of visualization that coding vids need
it reminds me of debuggers we used to have in the late 80ies
I finally understand Event Loop after 1 year writing JS.
Don't worry, many devs still don't understand it after 10 years of writing JS.
I thought I did… until today😅
No you do not 😂
huh do you need to understand it? coding js/ts for 3 years now
Then you're a shit developer tbh
Been doing javascript for over a decade, and this was the coolest explanation I've ever seen!
This is so important in JavaScript! Finally someone made a good video topic on this. Made me understood the call stack so clearly.
The sign of mastery is being able to simply explain a complicated concept. This preso is a thing of beauty... and mastery!
Top tier presentation, this is easily one of the best visualizations I've seen on UA-cam. You clearly have excellent teaching and communication skills. I know you are focusing your content on JavaScript but if you were ever interested in giving us an overview of some of your presentation techniques in Apple Keynote, I think many viewers could greatly benefit from it.
Keep up the awesome content! I can't wait to see what videos you have in store for this channel.
Amazing. I'm a visual learner, and it was a pleasure to watch and learn. Thank you for the content. 👏🏻👏🏻👏🏻
I can't believe, there is literally not one incorrect word here. Amazing.
I'm a web programmer for 15+ years now and I'm stunned how well made this explanation is. really Amazing! Subscribed right away!
The visualization is outstanding, providing one of the clearest and most informative explanations I've come across.
I'm preparing for an interview and this helps a lot. The promises video and this one are simply incredible. Love the series.
By far the most simple yet effective way to show event loop . Really enjoyed it
Lydia, your teaching style is the best I've seen. Please continue to educate us.
Thank you.
This is the best explanation I've seen.
Just jamming here... being C++ developer for 30 years, reading all these comments about seniors and juniors...I wonder: Guys have you ever read a text book about your profession?
Nice video btw!
Whoa, I'm so happy that this channel exists. The visuals help SO MUCH with understanding all the JS flow!
Whoaaaa... Ive been writing js for years and this is hands down the BEST event loop video resource ive ever seen. My god its presented so simply! 💯
This video brilliantly illustrates the intricate workings of JavaScript's Event Loop, Web APIs, and (Micro)task Queue. The visuals make complex concepts crystal clear, making it easier to grasp how JavaScript manages asynchronous tasks behind the scenes. Kudos to the creators.
Never thought I grab some popcorn🍿 to learn about the inner workings of JavaScript, yet here I am. Awesome work!
10 / 10 quality. The explanation of the different queues helped clear up confusion I had in the background of how asynchronous tasks work underneath the hood in the context of Javascript. Even with a bachelor's degree in computer science it was still a pretty head scratching concept thinking "how does the engine know what is I/O blocking and what is not? How does it handle that?". I would always hear "oh its just on the event loop! Its just on the event loop!" but I'd be like "all these diagrams suggest the blocking and non-blocking are on the same queue". I had no idea about the microtask queue and that is where fetch's then calls are appended to.
Also I can't help but look at the word "event loop" and just think of Froot Loops.
Hands down, the best event loop explanation ever!
this single video has taught me more about js under the hood then months of watching other videos
I have been programming for some years now, as a visual learner this video was awesome. Perfectly visualized and straight to the point! Keep up the great work
Fucking hell Lydia, this is incredible
Ah thank you Matt! 🙏
Thank you, Lydia. You explain very well. After 3 years writing JS, I'm finally taking the time to go back to the basics and learn the fundamentals and I'm learning a lot
I didn't know this was possible but this video is JavaScript meets Absolute Cinema
Are you Ai? This seems too perfect
*too (This has been your ai powered nostalgia post troll, have a nice day.)
Mam can you make a video on how exactly the react works under the hood ?
This is the best topic
I've never seen this information provided with such uncompromising clarity. Subbed. This is the first video I've seen of yours, but if the rest are anything like this one, you're worth it. Amazing.
I am in awe of the explanation and the masterful use of Keynote. Great stuff. Congrats!
This presentation is crazy good. I can only imagine the amount of work put into it. Congratulations.
Lydia, I want to encourage you to keep doing these if you desire. This visual, animated approach combined with your ability to teach is a home run.
You made it easy for me to understand the sequence of execution between the microtask queue and task queue. Thank you!
Okay it doesn’t look like me to just stupidly show appreciation, but this video is straight up great
Lydia, your explanation is by far the clearest i've seen out there. I'd love to watch something similar for async-await!
Congrats on this video. I've read a lot about this topic... articles, tweets, book passages. I've seen videos and talks about this. None of them were so thorough, clear and enlightening as this one. Keep up with the outstanding work!
The presentation quality is top-notch! This is probably the best JS "under-the-hood" explainer out there
This is absolute gold! So glad UA-cam recommended this video. Lydia, it is amazing to see the effort you've put into creating these slides.
I subscribed in the first 60 seconds. This is how the universities should have taught us! Kudos! Looking forward to your next one!
This was absolutely amazing!! The way you broke down callbacks from methods, visuals to see what’s happening. Best of all a challenge to really help drive the subject home, best way to improve learning. I can’t wait for more to come from you and THANK YOU!
I already knew all these but still watched it because of the quality of your presentation.
Great work.
Keep doing what you're doing.
I can't imagine the amount of work you put in to explain something so complex put so simply
I've already learned all this, but this is the probably the clearest, best, and most beautiful explanation I've seen. I need to share this...
This video is absolutely amazing! Very clear and straight to the point. I often struggle with understanding JS, and I found this video incredibly helpful. Thanks, Lydia! Looking forward for your new videos 👍
It's so well explained that after 1minutes 27 seconds of watching I had to subscribe. This is pure quality content
Where was this channel all this time. Great visualization. Thanks for all the handwork to put across all the details together.
This channel is a precious gem! Thank you, Lydia. I know it takes a lot of effort, but I hope you could make more videos with excellent visual explanations like this.
Your explanations are crystal clear and your slides are absolutely stunning! You have a real talent for breaking down complex topics in such an engaging way. Keep up the fantastic work, you're making learning an absolute pleasure!
Best possible explanation out there for understanding event loop concept in JS. Thanks for the video.
This video showcases a true understanding of the web api and the javascript event system resulting in a extremely high quality presentation.
Thank you! This is absolutely the best explanation I have ever seen. 12 mins of video cleared out all the my confusions I had in event loop from day 1!!
No BS just pure content! True GEM!!
Subscribed right away at 4:22
These small concepts took me a long time to grasp while working with JS over the years
Este video es INCREIBLE. Completamente deberia ser un MUST en cualquier capacitación/universidad. Millones de gracias!
I've seen 2-3 of Lydia's videos over the years (not sure if they are all of this channel) and they really are just phenomenally well-organized and delivered. I always learn a ton even though I have sadly watched a large proportion of JavaScript UA-cam and one might think I have seen everything. Well done Lydia! Hope to see more in the future.
The presentation and clarity of this information is excellent! Thank you for making this video. It made understanding the Event Loop so much easier!
Glad to be more clear about async stuff. Before just confused with the sequence and did not know why. Not even heard terms of promise based and callback based and their respectively being thrown to microtask queue and general task queue.
Thanks 👏
It is insane how much information you you were able to convey in one short video, I knew async tasks were pushed off to be filled later but I had no mental model how that worked until now.
This channel is a gold mine... literally.. please post more.
I think this is the best event loop explanation in the internet. You have described each and every point in such detailed way, making this topic feel so simple to understand. The animation is also made with such detail, making life easier.
Love all those illustrations. It really helps to understand the concepts. Thank you for everything you've done. Keep going! 👍
wow! the animations are crazy and helped me so much to understand what's going on behind the scenes! you also have a beautiful voice, it's so soothing!
So far the best explanation of how Java script works. Thanks
Wow! I'm surprised at how well the JavaScript asynchronous lifecycle is explained in this video. The best of its kind bar none.
beautiful and simple, Lydia great work. Thank you!
What you've done is mind-blowing, ma'am.
Well done! the best way to understand these concepts is with a visual explanation. Keep it up! 🔥
This is phenomenal. I just started learning javascript coming from an Embedded systems background and never understood how the execution of commands happened. This cleared a year of misconceptions for me and unprecedented years of troubles. Wow! Some people are just goated!
Lydia, this is the best explanation I’ve ever heard about this topic ❤ thank you!
Hope you keep doing this great job. This is one of the best explanations I've seen in the last few months.
this channel and fireship, kevin powell and web dev simplified is all a dev needs these days. Amazing job, keep it coming!
Super sold on the animations and slides. Ton's of work and dedication can be seen. Super awesome.
I must say, this is the best visual representation of JS I've seen so far
The slides really made it click, keep sticking to that way of teaching, that was great
This is a really great resource for learning the importance of the event loop.
This is the perfect medium between deep technical understanding and practical application of the event loop and Javascript as a whole.
Even though I knew all of this, I found it refreshing relearning with the way you organized information, and I even forgot about the Microservice queue so that cleared up some of my async JavaScript understanding.
This was an awesome watch! Looking forward to your future explanations/animations. Please keep it up 😁
Nice visual explanation of the types of stack n queues used for each call and the event loop lifecycle.
One of the best explainer videos I've ever seen, thank you! Subbed
Simply Great illustration of a seemingly simple yet inherently complex topic: JavaScript tasks and async / promise execution
12 min just recalled my last 2 years ❤🎉
Just wow! This is pants down the best Tutorial-Style-Vid I have ever seen. Please keep it up, I love it!
A brilliant explainer. Just what I was looking for coming from a Java ecosystem. Visuals are stunning. Thank you ma'am!
This was so well structured visualization and I was able to find the answer for the quiz correctly and I have become sure that the confusion around Event Loop/Callback/(Micro)TaskQueue do not bother me anymore. Thanks @theavocoder )
Thank you for detailed , visualised explanation Lydia!!!
Extremely well structured! The quiz in the end was a great idea
Got it right ! Once you understand the basics this is the best video ever to understand how the event loop and overall js engine execution work ! Thanks lydia
Absolutely loved your course on Frontend Masters! Super excited about your new UA-cam channel and can't wait for your upcoming videos. By the way, hands down, your lectures and the way you explained this topic is the best I've seen.
Amazing explanation on Event Loop. 100% would recommend to anyone who wants to learn about Event Loop.
Pls, don't stop making videos like this, it's really enlightening!❤
only 2 videos, and you are still killing it. Amazing content!