Jake Archibald on the web browser event loop, setTimeout, micro tasks, requestAnimationFrame, ...

"In The Loop" presented by Jake Archibald at JSConf.Asia 2018
Have you ever had a bug where things were happening in the wrong order, or particular style changes were being ignored? Ever fixed that bug by wrapping a section of code in a setTimeout? Ever found that fix to be unreliable, and played around with the timeout number until it kinda almost always worked?
This talk looks at the browser's event loop, the thing that orchestrates the main thread of the browser, which includes JavaScript, events, and rendering. We'll look at the difference between tasks, microtasks, requestAnimationFrame, requestIdleCallback, and where events land.
Hopefully you'll never have to use setTimeout hacks again!"
Jake is developer advocate for Google Chrome. He's one of the editors of the service worker spec, so he's into offline-first, push messaging and web performance.
JSConf.Asia - Capitol Theatre, Singapore - 27 January 2018
Source: 2018.jsconf.asia/
License: For reuse of this video under a more permissive license please get in touch with us. The speakers retain the copyright for their performances.

[@The9TKitsune]

When you want to be a stand up comedian and life makes you a JS expert

[@eritreanism]

on point :)

[@oleksii208]

hahahahah

[@markmhaslam]

Seriously! He's super funny. I would honestly love to watch him do stand-up.

[@LethiuxX]

Comedy is his hobby, it seems.

[@perfect.stealth]

Lmao

[@ronniesunshine1163]

Tough crowd, this is probably one of the best programming talks I've ever listened to

[@ReachByteBurst]

true

[@stefanplusplus917]

what do yo mean with tough crowd?

[@andy_lamax]

I agree. This was a tough crowd

[@bro...5849]

@@stefanplusplus917 he means the crowd is difficult to make laugh

[@TheMandySpace]

I was there, more people laughed than you think. :D But i agree it is one of the best talks Ive ever seen

[@buddhaburrito]

Jake is a truly genius presenter, sliding in jokes in between heavy subjects (like microtasks) so that audience can take mental rests

[@Nyromancer]

Humour is his hobby I guess. At least I find him funny, tough crowd...

[@jakearchibald]

In standup gigs they mic the audience too. They were more alive than the video suggests (but still pretty quiet)

[@JAlexanderCurtis]

Yeah I actually found his jokes to be pretty funny. I at least chuckled at most of them. My guess is the audience might have been giggling and chuckling too, but the laughter wasn't picked up by his lav mic. At 18:30 when he talks about the fizzy water, it's dead silent, but the way he rifted on it for a second indicates that he was probably getting a decent response from the audience.

[@Litonfiredesign]

@@JAlexanderCurtis Thats him that you responded too ;-) Great work on the presentation @jake quality. Thanks for your efforts.

[@utsavprabhakar5072]

@@jakearchibald Thanks for this !

[@erikachurchman9417]

wow

[@anonwithamnesia]

Who is here because of Fireship?

[@starhopper4587]

🙋🏻‍♀️🔥

[@shimin_mathew]

Me me 🤗🤗

[@herohamp2]

Hola

[@mykhailomikhnovych8303]

yup :)

[@AmanNidhi]

me during may lockdown covid

[@JaLikon65]

Why on earth did people not stand up and cheer after this! This is EASILY the best talk I've ever seen on the JS event loop and related topics. Seriously, it takes other resources like 20x the time to explain this, and this is arguably more thorough then a lot of other resources. Just hats off man, WOW is this good.

[@DonaldFranciszekTusk]

Robbers' talk was better.

[@LichardD]

Came here to learn about event loops. I now fear those who drink fizzy water.

[@benoitleger-derville4162]

Best show and explanation ever about the the V8 event-loop / main thread / tasks / microtasks

[@dinub8414]

Yep. Thanks to Jake! Worth mentioning, though, that the event loop doesn't run within the V8 javascript engine, but natively in the browser. The javascript runtime has no own event loop. I found Phil Roberts' talk very good, too: kzbin.info/www/bejne/bpKqmY2HoNR5mLM

[@SamiullahKhan]

He really hit the core of the event loop. Something that is so important to get hold of tasks, micro tasks.

[@dakedres]

I love how it feels like he's going on completely unrelated tangents but it always seemlessly transitions back into the main idea

[@vishnusingh4118]

7:08 Task Queues 8:55 render steps 12:15 hence the timeOut loop is not 'render blocking'. 12:29 but if you want to run code that has anything to do with rendering, a task is the wrong place to do it, coz it's on the 'opposite' side of the world from rendering, as far as the event loop is concerned. 24:00 MicroTasks (RAF - RequestAnimationFrame finishes here )

[@herzallahaymen5478]

give us a smmary of the jokes

[@InternetTips_bb]

Jake is an amazing asset for the JS community!

[@codeaperture]

I always watch this when I feel " you don't know JavaScript yet,,"

[@atticoos]

Hot damn, Jake.. this is one of the best talks I've seen. Well done.

[@maximlyakhov967]

This is the best event loop talk on YT. Well balanced mental load / mental rest. Thank you, Jake!

[@justinhalsall4077]

Love Jake's talks, always super solid, informative and even include some giggles from time to time!

[@XAbybai]

I repeat others, but I want to give the great thanks to that speaker. Very very nice talk about loop, promise, RAF and others tricky cases. Thanks you a lot!

[@anjaliRaghavmgr8]

Loved the energy he brings to the talk. Informatively hilarious!

[@ananthakrishnanj729]

Most informative and engaging talks on event loops! Kudos Jakes.

[@Ashok-wc9be]

This guy is super awesome and this talk is probably the best talk on the event-loop out there! Thanks a lot!

[@MiltonSosa]

Amazing explanation on how event-loop, RAF and micro-tasks works!

[@markovujanic]

This video sits much better after third time 'through the loop'. Thanks Jake for creating it.

[@AmandeepSingh-hd8iq]

Now this is what you call a talk. Impeccable 👌

[@jlyunior]

This talk has to be displayed in the best Cinemas :) amazing talk 3 years later and im totally sure that will be a good talk to watch again in 2035

[@MajorBreakfast]

Thank you for including the part about microtasks! Very informative!

[@Pupu._]

great video! I might need to watch again to wrap up the concepts but he's a great speaker with fun ! I hope he gives us more talks like this

[@kieran2347]

Thank you for explaining event loops for all of us 5-year-olds, Jake! You the best!

[@ashishshubham]

I wish I learnt all my CS courses from you Jake.

[@indylawi5021]

Great, fun to watch, very intuitive (with a good sense of humor) presentation for a deep insight into what is going on inside the JS event loop. Jake, you definitely nail JS event loop.

[@shivam.mishra]

Never had such a clear vision of the event loop. Thanks jake

[@JuanOrigami]

The piano chat part is totally relatable. When i do a talk in front of thousands of people I want to be as funny as this man

[@Gelio1234]

What a great talk! So much useful information presented in a convenient and easy to understand way

[@xingyuye0313]

This is the best talk on the "event loop" I've ever seen!

[@dima9740]

Oh my gosh, that's very simple, clear and informative. Great speaker, great presentation.

[@c9988774455]

I never Heard about Microtasks even though I am using Promises, Great visual comparison between JSTasks, rAF and Microtasks. Awesome stuff Jake.

[@mr_ozio]

This is the must watch video before any js interview.

[@smitthakkar9837]

One of the best talks till date on event loop! Thanks a lot!

[@jasonsebring3983]

I feel like I just started learning this stuff and I've been doing it for so long. Amazing!

[@__azt]

Wow! That is one of the most informative talks I ever heard.

[@cli23]

Amazing talk in so many ways. Incredible speaker, slides and diagrams, and content.

[@Textras]

Superb talk Jake. As always!! Now time for a lime soda water.

[@ShahriarAnwar]

Just AWESOME. Jake you're my man.

[@paavangupta3420]

His way of explaining things with so much clarity and hilarious jokes in between, is on the next level 😂🙌 Amazing!

[@mattscheurich1037]

Super great explainer, whoever did the design for the animations deserves a massive shout-out. Well thought out and great visual metaphors too.

[@jakearchibald]

I do all my own stunts

[@rizaldywirawan]

​@@jakearchibald Full Stack Speaker, i guess :v ... Can you tell us what software do you use or how you create the animation, please?

[@mreyybree]

@@rizaldywirawan He uses HTML+CSS+JS+SVG

[@raymondyoo5461]

wow great lecture. Talking about deep and complex notions in such a concise tone, thanks for your great presentation

[@feihcsim7045]

my man jake killing it again

[@dnav10]

Didn't know anything about this. Now I feel like wanting to dig more into JavaScript

[@tinpham6413]

This is the best presentation so far i've seen from the badass talking and animation for slide, but sad for the dead crowd

[@shenoynishant]

This is awesome! I had developed a parallax feature using rAF, and I was wondering why it was smooth on Chrome but janky on Edge, this explains it :)

[@dacao9240]

I want to download this video and save it in my laptop, just in case youtube goes down. That's how much I love this video.

[@sudeep.g]

One of the best talks I have ever seen!

[@Imsganesh]

Great talk. Elegant and simple explanation!! 👏👏

[@ashokethapay]

What an amazing talk. It cleared out lot of my queries around the event loop, when the browser prepares a frame, and how much javascript it runs before the frame. Thanks, Jake!!!

[@faceupanddown]

You can have a new hobby at which you are extremely good and it's technical presentations about JS and web. Aaaa, also, the how different queues are processed made shivers run up my neck. Really excited. Wife (who is senior QA) is getting jealous of you :p

[@SafetyLast-_-]

The best explanation of the Event Loop out there 👍

[@nukebarbarbarian3735]

This is the best video on event loop so clear!

[@maximofernandez196]

"You don't want to write a code that is like a sneeze". Yeah, this is probably one of the best talks I've ever seen, actually pedagogical if we think about it

[@promatik]

What a great feeling, just learned awesome stuff. Thanks!

[@johnlennon407]

Wow, what a fantastic performance! Entertaining and informative, with deep philosophical thoughts like sneezing metaphor or orbits and sun animations. The lector is brilliant.

[@SocksWithSandals]

I was that guy who would throw in a setTimeout and play around with the delay number until the manual test matched the automated test. It would raise an eyebrow at code reviews, but I'm a pragmatist not a purist. Now I know why I was right! Thanks Jake.

[@Munchyydl]

Great visual explanation of the event loop! :)

[@user-rz7kz7qv8z]

this is awesome, really well explained.

[@amanmavai99]

one of the best talks I have ever seen. !!

[@havenoideawith]

Love the main thread animation.☺️

[@karadelamarck6576]

Thank you for an excellent talk! Fascinating, especially regarding promises and microtasks and how the microtask queue must run to completion before the event loop can continue. Could I ask how callbacks and promises (both of which generate short-lived objects) are affected by, or affect, garbage collection? When the new space is full how does the V8 engine handle the 'stop the world' technique in relation to the event loop? Is there a potential for callbacks to be more performant regarding garbage collection vs promises?

[@bg_x6558]

This talk is soooo informative. A single effective visual plus narrative beats a thousand words. Could someone enlighten me of the tool or the way for the speaker to make the slides (or something else) ?

[@DheerajBhaskar]

I'm also interested. I think he used HTML5 and js to make this

[@ys5399]

I think I know you from Columbus Ohio??

[@norwen]

Thank you for this amazing talk! Whole new world :)

[@shikharchaudhary6984]

Amazing talk. Cleared my concepts. Good Job !

[@user-db2bl1oj1v]

Amazing video. You make the subject very clear

[@saurabhmehta7681]

Great talk! And his level of understanding is inspirational

[@sgwatyt]

The main Fred.

[@jakearchibald]

I find it very difficult to discuss the movie Thor.

[@omarflores4234]

i cannot unhear this hahaha

[@hobbyturystaSEO]

:D

[@nikosc]

Wow. After that talk I used many blogs and MDN docs to fully understand these topics.

[@thefuturejulio]

I feel like I just watched epic blockbuster with huge budget, Tom Cruise and stuff

[@faceupanddown]

Same!

[@mr.fishfish570]

Thank you very much for doing this presentation!

[@PaulShmaul]

Best explanation of event loop, indeed

[@waldemarenns4874]

A classical Archibald. Great talk!

[@mryechkin]

Man.. tough crowd! This was a great talk

[@EduardoWeidmanBarijan]

That was easy to follow even though I get stuck a lot when it comes to frontend programming. Good job.

[@shuvenduoffline]

Best explanation you can find

[@zubinix]

Great explanation. Thanks Jake.

[@HarshSingh-hk8fe]

this is the best explanation of even loops

[@herozero777]

Yup this is really helpful, thanks for this awesome talk.

[@KaranSheth]

This is so good! Its like Simon Amstell coming to teach me about javascript stuff!

[@dattugaade]

It's very informative. Thanks Jake.

[@gabrielt6756]

Beautiful talk! 🙏🏻

[@afca25]

That's a tough crowd if i've ever seen one... My man is killing it there!!

[@MerrStudio]

I love this talk, great job

[@danieltroger1761]

This talk was SOOO GOOOd. TYSM 🙏

[@AhmadAwais]

Just like always, amazing presentation, especially when you magically swapped those lines around at 2:25 😲

[@fadedlama]

nani?!

[@Manish_Singh_Chauhan]

Awsmeeeee JAKE! Thank you! :)

[@stackdeveloper6614]

My life as a developer changed after this talk!

[@HenleyBailey]

Great explanation, thank you.

[@abdulnaveed4984]

awesome explanation sir great, really love to listen you

[@shizueigaki702]

Absolute legend, this man.

[@1kounter]

clear and simple explanation for a beginner to get a grasp of what is going on under the hood, well done! Correct if I'm wrong but I think there is a mistake in the little exercise at 30:32 . It should be promise.then('Microtask 1') instead of promise.then('Listener 1') and same for number 2.

[@inzmamulhassan]

best video to explain event loop

[@Systemv1]

Well done buddy, great talk, thank you 🎉

[@xerxius5446]

Finally, a JS expert with a sense of humor !

[@JulianSloman]

That laughter at the end "back to the studio" :D

[@sebastiaanhols9103]

Excellent explanation 👌

[@anirudhsreerambhatla6108]

This is one of the best talks I have seen after Phillips Roberts What the heck is the event loop? Both these talks helped me understand the Event Loop and get better context I then took the JS the Hard Parts from Front End Masters by Will Sentence. It was great. I got a better understanding of the the async and concurrency model of JS

[@kf88743]

I have followed the same path, except in reverse. I came here after watching all of Will Sentence's videos on Front End Masters. He is by far my favorite instructor there.