Are you bad, good, better or best with Async JS? JS Tutorial: Callbacks, Promises, Generators

The 4 levels of clean JS ASync programming: Javascript programming can get really ugly, really fast...but not if you know how to avoid "callback hell".

Also watch this video - ES6 Generators

Level one: Programming with callbacks - you make it work, but it's ugly
Level two: Programming with abstracted callbacks - cleaner for sure, but still messy and way too much repeated code
Level three: Promises - much cleaner much more stable code, but still not as enjoyable as code should be
Level four: Generators - life is good.

This is a javascript promises tutorial / javascript generators tutorial. We're going to show the four levels and why each level is better than the one before it. Along the way, you should learn a decent bit about promises, and even some about generators.

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Also watch: "Responsive Design Tutorial - Tips for making web sites look great on any device"
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[NishantGupta_Neo]

You Sir! ... Are legendary when it comes to explaining hard to understand stuff !

[ntokozonkosi]

What I couldn't learn in 2 hours reading about promises, it all made sense in 14 minutes watching this video. I had one of those Wow experience here. Thank you very much man your teaching techniques works thumbs up

[xximo]

I am never satisfied with programming video tutorials. You Sir are the exception.

[NeilTruick]

Will, you are a rock star! You've saved my life again...

I'm using Sequelize as my ORM on a current Express project. Sequelize uses promises throughout, but the examples don't help you understand promises if you don't already know how they work. I wanted my API routes and my Sequelize models decoupled, so I could support multiple database platforms for development, testing and production. My searches on Stack Overflow sent me down the callback path, but it just looked too confusing to me. A YouTube search on "javascript callback functions" showed this video fifth or sixth in the list, and I went straight here, because Will. 15 minutes later, my decoupling is working better than I envisioned! I've said it before and I'll say it again...you are a masterful communicator. Thank you...

[aryaravish]

One of the best videos on promises on youtube. Crystal clear. Thanks a lot.

[drikting]

Callback refresher and more! Indeed, Generators looks cleaner - Thanks for the share and effort to do these professional videos!

[nafishasnian]

Man you are the best Teacher ever! I like the way you explain EVERYTHING so clearly. You are definitely better than most university teachers.

[theway]

The best and evolutionary approach to demonstrate necessity of promises and their next level abstraction. Great lesson!

[veeweeherman]

I've been watching your vids for over a year now. You rock. Thank you for posting :D

[freemind]

Amazing tutorials, you are probably the best I've seen regarding teaching coding in general. Very knowledgeable, interesting and great at explaining. Feels like I'm learning from a real professional!
Thank you!

[alexandersobolev]

Very clear explanation! Man, it is truly important to have a right mentor and materials when you learn programming. Because when it is explained in such a way you do it, all these complicated JS concepts become easy. I really enjoyed this tutorial.
P.S. In such moments I wonder why Youtube doesn't have a triple like button!

[deelanmj]

This was clearly explained! Finally understood how promises work. Thank you! Subscribed ;)

[VladyVeselinov]

Hahaha, "the code must go on", you rock Will!

[karankaw]

Good Way, Better Way, Best way and Awesome way!!! - You nailed it neatly, mate

[nickang]

This is UH-MAZING! Thanks a lot for explaining (successfully) the thing I've been stuck on for over a week. :)

[kamillatosinski]

And the Nobel Prize in simplifying things and explaining hard things in an easy, understandable way goes to... wait for it... Will Stern!

[SANDEEPAGRAWAL]

Nicely and easily explained promises by taking a comparison with other ways of JS ASync.
Your video was helpful. Thanks.

[fancyydk]

Very helpful! Promises make so much sense now. Thank you!!

[chibsryder]

You are pretty awesome friend. Thanks for explaining all these concepts in a simple way

[kebien]

Thanks! I just refactored a bit of code and now its really beautiful (to me, at least)