FASTER JavaScript In 2025 With Sets

[@pawel_890]

The set is great only under few conditions: - you don't do frequent addition, because each element has a calculated index - you can't update existed elements - just use Map - you can't refer after index `array[index]` - just use Array Set is something like an object `{}` with built in an iterator

[@yobebill1234]

everything is an object jerry.

[@designerjehovah4453]

Glad to have you back Jack!!

[@jherr]

Nice to be back from vacation.

[@mounis]

Wake up babe, new Jack Herrington video just dropped.

[@acrosstundras]

When it comes to performance, the answer is, more often than not, "it depends". For example, in some situations, array lookup will use CPU cache, whereas set will not, resulting in worse performance counterintuitively.

[@mahmoud-d22]

Happy new year Jack :)

[@rogerscript]

New Year, but the same awesome quality of your videos Jack! Thank you to be back!

[@NaserPapi-x7z]

Excellent Exploration; I really appreciate your technique for teaching this fascinating topic. Personally, I enjoyed the performance part and your demo of the O-one vs. O-N lookup. Thanks for this great sharing.

[@ahoy1]

I used Sets for the first time a few month ago, they're great. Having union/difference/etc methods built right in is great

[@RossOlsonDotCom]

Great tight overview of this! The one thing I’m missing is the types that are returned. It looks like some of the set operations will return arrays, but some could return sets. It would be great to know which is coming back.

[@shinebayar]

Btw performance difference is negligible if you're working with small data set like under a thousand or something. Because of the array values are stored next to each other in the memory and it's faster to lookup them if the entire array can fit in the cpu cache.

[@yamelamadorfernandez7416]

Honestly I've used 30% of the Set features, watching this video reformatted my brain, now I realize that Set is very powerful and closer to Array functionality than Map.

[@JoshMarom-zx9mv]

Great content as usual

[@dkazmer2]

Best video on Set I've seen

[@alexlohr7366]

The Set in JS is a hash set with fast collision handling under the hood. By the way, there is a solid-primitive for a reactive Set that you'll like.

[@MohammedWaseemAnjum]

Thank you sir you are awesome as usual!

[@aaronstarling9837]

Awesome information!

[@reneheijdens8444]

Great video! I've been using Set to generate arrays with unique values, but I never realized its full potential until now. 😅 Quick question: How do you use Set effectively with objects? Since the uniqueness constraint relies on object references, does that mean it only works if the objects reference the exact same memory location? Also, is it possible to extend Set functionality to perform operations like union, intersection, and difference when dealing with objects? Would love to hear your thoughts or see examples!

[@jherr]

You can just do something like: const keysA = new Set(Object.keys(a)); const keysB = new Set(Object.keys(b)); keysA.union(keysB); keysA.symmetricDifference(keysB); // etc. You could do the same thing with Object.values(). Depends on your use case.

[@josersleal]

even I could understand that at first at 1.5x speed. well done Sir. On notebooks, there's also microsoft new offering: polyglot notebooks extension. you can use multiple languages in the same notebook and share variables between them. create diagrams and more. no typescript yet though.

[@jherr]

Ooof, that last sentence is a killer. No TypeScript? From Microsoft? Booo... Otherwise, sign me up!

[@lastink444]

I'm actually more surprised/impressed by the jupyter notebook here

[@daxdivv]

How do you get those auto completions at 0:41?

[@lakshmanshankar]

I'm not sure what that was but it looks like warp terminal.

[@dannrcstr]

First you must have a MacOS, then install the ZSH terminal (version 5.8 or greater), then install and configure the zsh-autocomplete plugin

[@sikritidakua]

I think it was something called `fig sh` I used it in the past but I removed it later, it was very annoying for me

[@dannrcstr]

@@sikritidakua Fig has been discontinued

[@sikritidakua]

@ yeah its Amazon Q cli or something i dont remember correctly but if u search fig sh it will come

[@adrian34234]

Great video I really like Set a lot! Can it be used in js already?

[@jherr]

100%.

[@youarethecssformyhtml]

They're so old actually (released before 2016) so yeah

[@adrian34234]

@@youarethecssformyhtml So why is there more noise about it now? I'm curious

[@youarethecssformyhtml]

@@adrian34234 no idea

[@dkazmer2]

@@adrian34234 cuz clearly nobody knows about it still

[@mannuelf]

Great great great 🤘🚀

[@Mizax22]

The translation in French is truly top-notch 🎉

[@MrJettann]

Do we need use usecallback on functions passed to set?

[@jherr]

Yes. You want references to functions in React to be controlled, which is what useCallback does, regardless of where you store them. And in particular with Set, you are using the memory location of the function as the unique key, so, yes, use useCallback.

[@Ivan-wm6gm]

javascript team should really add priority queue

[@deatho0ne587]

O(1) is not always faster than O(N) since you need to care about things like creation, deletion, etc... times. The testing of the speed is kind of bad to be fair. Data is normally never in such a simple order or just number. I do like the examples of some set comparisons to be honest.

[@codehan]

Thanks! 🎉

[@flydown1940]

name of vscode theme?

[@jherr]

Night Wolf (black)

[@bryson2662]

What is the point of Set.entries?

[@jherr]

Compatability with a family of data structures. Map, Set and arrays all support `entries` directly. And Object.entries gets you entries for an object.

[@nuwanthuduwage6869]

Cool!

[@ggnova8581]

Theme?

[@jherr]

Night Wolf (black). Always listed in the description.

[@ggnova8581]

@@jherrmy bad I didn’t see that

[@jherr]

@@ggnova8581 No worries. Just referencing it for future commenters. (Actually I shouldn't, more comments is good. Hahahah.)

[@danser_theplayer01]

A few notes if you care about performance (maybe you're doing servers or science): - Sets are bad at iteration as they use generators which is actually very slow compared to a *for* loop. The same can be said about any object that let's you use *for of* or spread *...* of values, because those are also generators (... isn't always though). Generators and callback methods like forEach() are inefficient (at least generators bring some neat special functionality), and fall off hard after a certain point. It's especially true when generators yield other generators.

[@ryosukekureha4873]

잭형님❤

[@ryankdavidson]

Monday morning Jack Attack 💥. TIL Jupyter can be used with JS via Deno, great side takeaway from this.

[@nro337]

Great video for performance!

[@M1a2n3o43]

Wtf you can run javascript code in a ipynb file?

[@SrAzion]

so normally it depends on the algorithms

[@nathanalberg]

who comes up with these names?.... `set.difference` should be `set.without` and `set.symmetricDifference` should be `set.difference`... i mean... wtf. symmetricDifference?

[@jherr]

Mathematicians. Difference and Symmetric Difference are well defined terms in Set Theory.

[@LutherDePapier]

At 8:36, when a developer accidentally creates an array of 300000 values, JavaScript as a language should have a built-in mechanism to turn that insanity into a Set. ECMA team if you're listening.

[@jherr]

Hahaha. That would be terrifying. There are key semantic differences between the two.

[@WCanyon]

good video -- you're talking kinda fast in here though

[@thearcticmonkey]

Decrease video speed

[@jherr]

And here I think I'm always talking too slow. Hahaha. Yes, decrease (or increase) playback speed to suit.