If this ships, it will change javascript forever
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- Опубліковано 28 вер 2024
- Signals in JavaScript might be at Stage 0, but it's a very exciting Stage 0 proposal. My love of Solid forces me to be hyped
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S/O Ph4se0n3 for the awesome edit 🙏
Javascript: The new javascript framework
we will eventually get there lol
Predictable and good
JavaScript is the new JavaScript
😮
It's funny that we need the term "signals" when it's pretty much just a particular version of that good old observer pattern
this
Right? "Signals" is confusing the hell out of me because this is nothing to do with signals.
It's a signal because it's a two way thing. Push dirty flags towards consumers when root data changes, and push recompute requests towards the root when the new data is needed for consumption (and also do no recompute when inputs don't change). So it's a lazy, two-way observer pattern.
@@W1ngSMC exactly
currently playing with LegendApp state and even syntax for basic stuff is almost identical
Vue has had signals baked in for many years but with a nicer syntax. It was based on KnockoutJS that's ancient.
Yea, _very_ disappointing to see how Theo glosses over the OG and state of the art works cause it just ain't give clickz.
Also can define computed get and *set* abstraction in Vue. Very useful when binding.
They use proxy objects to attain this functionality
Meanwhile Haskell devs: "Look what they need to mimic a fraction of our power!"
At least JS and TS ship once in a while
And that’s the point: they want a minimal base that provides the most useful parts without forcing laziness as default.
Not just Haskell, seems people are starting to understand that declarative is future (and I'm 100% sure imperative will die, as is spaghetti nonsense in long run), so instead of fully committing some salad gets invented. Which is still progress, but still. As shown by polyfill it was doable all along :) I guess just "environment" (read people) need to grow.
@@morphles isn’t that what the prolog people used to say?
@@ArneBab Only in a couple of days later, they need to wait for their proof of concept to finish evaluating.
So much about Signals reminds me of how Jotai is designed. The whole atomic state like each signal represents, and having derived state similar to signals.computed. However signals takes it a step forward by not re-computing the graph when the root node changes, but only when a specific node is consumed. Clever!
Thanks for pointing this out. Been following various signal based systems (including early elm and purescript) for a bunch of years. It's neat to see that they're tackling rendering timeliness, out-of-date-ness and effectfulness. It's easy to write a signal graph but very hard to get the consumption API right. Don't feel great about the amount of work left to the consumer in the blog post, but we'll see how it falls out. There's nothing worse than writing something nice in a reactive system, adding one more component or relationship and suddenly being without a paddle trying to track down a lost or retrograde ui update.
Somebody on the design team likes knockoutJS 😂
Exactly. Pretty much the same thing.
Having worked on a KnockoutJS project myself for many years (2014 - 2018), this was exactly my thought 😄
First of all, I've subscribed because I really enjoy your manner of delivering content. However, for the longest time, I was trying to figure out where I know you from and then it hit me. Has anyone ever told you you look like Lalo's (from Better Call Saul / Breaking Bad) healthier younger brother? I can't unsee it now!
Thank you for the content, your channel is awesome!
lalo lite
After 2 years of adopting this" this feature has been deprecated "
YUP YUP! The profiles of the proponents worry me... I don't see their future. I don't see the future of their work.
yep the rate this got adopted gave me pause. i did recently realize mithril.js has had a hacked-together unintentional construction of half of this (in the style of every program eventually growing a bug-riddled half-implementation of common lisp) since its first release 10 years ago (2014 march 17), so that makes me feel much more like it's truly on to something. (i'm also a former maintainer of mithril.js, so...)
It's basically Vue's reactivity system which preceded SolidJs and was inspired by KnockoutJS instead. Let's give proper credits please.
Imagine the implicit mutations that's not trackable where you can mutate a signal in a different file and it triggers a bunch of changes in many others.
You can use the initial/ current polyfill in production by using Angular :P - jokes aside the current polyfil is based on the signal primitive that was written in Angular to be shared with WIZ
i want to note that, signal is not really a lazy value, because it retains it's value in the memory unlike the observables.
A nice and declarative way to optimise data trees, I like it! It probably does still need some iteration, but the concept sounds great.
Something this doesn't seem to supposed is parameterised signals. I don't know _how_ you'd support that in a performant way, but it would be nice to be able to call something like `const a_or_b = (x, y) => a(x, y) || b(x, y)` in a performant way. Memoising something like that seems like a pain though, so I don't really want to open that can of worms, especially since I haven't yet run into a use case complex enough where performance is a major issue for chains of computations like that.
no, it's pretty simple, you just use an object or a tuple (array?) I guess. Been a while since I used JavaScript but in Rust I just use Tuples and Structs as the parameter type, it's just like having multiple parameters.
@@Luxalpa You mean a map of arrays representing the provided arguments? That doesn't work because Array isn't a value type, so they'll never compare as equal and you'll never be able to find anything in the map.
Interoperability would be SO GOOD for the web. I would have already switched to Solid if not for the fact that so many of the react libraries I use don't have a good equivalent in the Solid/Start ecosystem (e.g. clerk, trpc, react-pdf, react-markdown, sonner, etc)
Is that what Xerox had in the 70ies? And Qt since the 90ies?
Probably one of the most wisest proposals in a while.
I don't understand why this is necessary. All of the examples that are given in the blog can be done by functions in a simpler way. This doesn't seem to solve anything.
Exactly! I'm not too sure about this one
It's more efficient, and allows less JS to be shipped for frameworks that leverage their own implementation of signals.
Functions are not reactive though. I do see your point as passing a function around that wraps a variable will have access to that variable.
The use case is passing a variable around and updating it. You want the original variable to update even when it is assigned to another object property or anywhere it is updated, up and down the chain. You don't get that unless you only pass the original.
Essentially, as soon as you assign to the value, it loses its reference or copy on write. With this, it doesn't matter where the update happens, it would update anywhere the variable is used. Granted this is technically true with any object.
I agree. It solves a problem that frameworks added, and it can be solved by existing features. This only needs to be a package.
Because implementing these primitives on a browser level opens up room for allot of runtime optimizations, its very likely every state framework will use these primitives if they are implemented well, because it would save a ton of performance
Why does it sounds exacly like Vue's computed ?
I wonder if it is actually going to be composable with higher order functions and adding your own abstractions on top of it or if it is going to do some kind of chaining syntax that basically that really difficult to do and you're stuck only working at the lower level of abstractions.
Elm had signals too in 2015, then the community collectively got over it - sad to see history repeat in JavaScript
Not sure if this is a good idea or not but if we need another data wrapper implementation I would prefer it to be native. I'm sick and tired of expanding proxy objects in the debugger to get the value of simple variables.
This is Excel for programming languages. AKA Microsoft Power Fx.
you either become lisp or excel nothing in between
Ben Lesh is not the creator of RxJs. He is currently the core/ lead maintainer of RxJs.
When it comes to recomputing everything that depends on the given entity after it's changed... um, we already have this functionality in the form of React memo, right? If I'm interpreting this code correctly, signals do the exact same thing with a different syntax. Instead of including Foo, which is a state value, in the dependency array of memoized Bar, you turn both entities into signals, and use the "Computed" function to create a dependency between Foo and Bar. If this is how it works, then it isn't THAT different from what we already have. I'm probably misinterpreting it, though, since I've never dealt with the concept of signals.
What is the poin of this qhen you can just do this:
let a = 6;
let double = () => a*2;
double()
outputs 12
a = 12
double()
outputs 24
Like, why put the value and the inline method inside weird objects when you can do the same by just using inline methods?
Ok, understood, why not use functions? Why do I need the dependency on a "source" or want a "sink"?
What's wrong with using functions (even lambdas) for that?
tagged template literals + signals = React in vanilla go brrrrrrrr
With regards to effects only being for framework authors: This makes signals useless outside of frameworks (for anyone who is not a framework author anyway), since there is no mechanism of being notified of updated signals/values.
It sounds like this 'primitive' is only intended for use in frameworks, which is super weird and kinda dumb.
I would love to understand how you think current signal implementations are FP? just because signal(...)? Because at least to my knowledge they all rely on one or another form of graph representing them, which is in my book not FP
It would be nice if we all had one shared standard for signals, however I don't see why this needs to be a part of JS itself.
Why not just make this a package, or leave it a polyfill?
Seems too niche to expect all browsers* to handle this complicated a set of behaviors when they barely handle CSS the same way yet.
There are already many niche features that browsers implement that don’t see 0.0001% of use even. This will be far more valuable to be included in the web spec.
@@azizsafudin It's useless to anyone building frameworks if half the browsers don't support it. Imagine if react only worked on chrome because they chose to depend on chrome specific APIs. Doesn't make sense.
Vox populi was huge with cicada 3301 and is crazy with cryptography stuff. Odd to see him in JS land
Sounds to me like like the javascript equivalent of quantum enganglement
So this is more of a change to the web standard library, right? That feels not as ground breaking. It would be cool to see some syntactic sugar that makes the dev experience better. Just like how Promises were ground breaking when paired with the async await syntax.
This should be a library, not a language feature (and "new" should be deprecated in JS)
so using lib like valtio is just like temporary solution until this officially supported on JS ?
They hated vue so much they decided to copy it🤣
Adding Signals directly to the JS Runtime makes a lot of sense and moves the web platform years ahead. The key pattern around Signals is the Gang of Four Observer pattern which is key pattern to drive data binding. Don't tell Theo most modern UI libraries use some form of the MVC pattern. Model (State), View (HTML) and Controller (Component).
Is there a value to these beyond what getters provide?
Theo, you hate web components because they're bad idea or because their API sucks?
Like I think the concept is good - it's just that sharing state between them or using CSS sucks, API to define a WC sucks but the concept is good imo.
TLDW; literally Svelte stores for vanilla JS
why dont you just how that works? 3:43 and of you can go up in hierarchy in react if you pass the components without creating a deathloop
WHERE i can get this twitch-cup?
heisenberg effect??
So does this steal react-forget’s thunder?
Should react support and promote signals over hooks?
No need, you can definitely write wrapper for that in 5 minutes based on get set 🤷🏼♀️ also you have something similar in nodejs already
The big win of Signals in the spec is not payload size or performance, it is interoperability. If this happens, it will be as impactful as Promises. It is not only about sharing code and state between frontend frameworks, but also replacing any kind of set+onchange interface out there, just like Promises replaced callback hell.
I feel like a baby because I have used Promises from day 1 and do not know a world without it. But I can see why signals would be as impactful
Its okay @csy897
Yeah looking at old axios code in large apps is just... Mind-blowing honestly 😂
> "Like Promises replaced callback hell"
Out of the frying pan and into the fire, e.g. async/await "two-color" function hell! 😢
@@gearboxworks to clarify, Promises are independent from async functions. But yeah, I feel you.
So like Vue state (ref, computed, etc...) but in javascript itself?
Seems like it
No, it’s like React state (ref, memo, etc…) but in javascript itself.
@@fullfungo no
Looks just like Vue. But I'm happy for all of you who are stuck with React because you might finally get a proper reactivity system lol
bro redux selectors predate vue
@@klausburgersten yeah they probably do... whatever that is
Dude bro
@@vincentv8991 dude
Lol
CanJS has had this since 2013 but so few people know about the framework that all their innovations went largely unnoticed
Knockout js also had since 2010..
I used CanJS and also its predecessor, JavaScript MVC.
It's weird how we had all these great frameworks and they all disappeared and were replaced by React.
Also, what happened to Polymer framework???
IMO, Polymer was superior to React but very few companies used it at the time. I guess at least now there is Lit... But you don't really even need a framework at all nowadays. Web Components is powerful stuff.
@@Remindor Vue is actually the most popular one that was inspired by KnockoutJs but the video doesn't mention that somehow.
@@ziad_jkhan … Vue is _explicitly_ called out at 13:15 as one of many frameworks that have provided input on the proposed spec.
@@Remindor WC’s are super cool. Lit does at least purportedly help take some of the boilerplate out of writing WC’s. I haven’t used it yet but considering experimenting with it.
A number of concepts here that are very vue.js. Would love to see this in core js
the concept of computed is the same from Vue. As some one who works with Vue2 since 2019 I can say these people are way behind Vue and this nothing too fancy or to be excited about.
@@MrDragos360vue has done a terrible job at marketing. I had a job interview recently where a senior frontend dev told me their company moved from vue to react for WAIT FOR IT performance reasons 🤣
Evan you is also part of this proposal and he tweeted recently regarding this.
getting signals into js itself would help vue performance wise as well. Being able to share vue ref states with other js frameworks/apps is also nice. But yeah vue already has most (or all?) of this and it's one of the reasons why I use vue when I get the choice.
I don’t hate Signals but putting things into the language this keenly is exactly how JavaScript ended up this way.
Having said that, the performance advantage of lowering this work to a language primitive (think executed in C) would be huge. I would like to see what syntactic sugar like they used for async/await might look like because the library is ugly to use in the proposal.
i think it makes a lot of sense to put it in the language since almost all popular frameworks use it, but i do agree that we need to be careful!
I loved KnockoutJs and still have a fairly large codebase using it,, I find it hilarious the world is coming back round to what Knockout did in the first place.
Unfortunately I also have a huge codebase using RxJs and React, so swings in roundabouts.
Rob Eiserberg is the one who created DurandalJS a decade back, which extensively used knockoutJS for reactivity. Definitely got inspired.
I feel like we're getting closer and closer to "framework singularity" because most people agreed that signals are something worth implementing and using. Maybe at some point the difference between frameworks will come down only to syntax.
And some edge case performance optimizations, and framework interoperability... Probably
I think 15 years from now best features of every framework will be native and we'll just write vanilla JS.
State management is indeed core and central to every framework, but there's much more to it.
JS, and by extension TS, are the fastest moving languages in history. Love it or hate it, JS is the social programming language. That gives it the highest adoption, thus the most iterations/collaborators, thus the highest likelihood of becoming ubiquitous to the point of absorbing all competition. See: AssemblyScript (TS->Assembly); Hermes Static (TS->C); Frameworks are no exception. Resistance is futile. All will be assimilated.
It all return to nothing...
It's unfortunate that "a sink" and "async" are homophones.
Maybe a intended pun
Really really close. They sound different in my head but I can see the source of confusion in non native speakers
I say “a sink” as uh sink and “async” as ay sink
But usually the context in which the two will be used will be disambiguating. It’s probably only ambiguous without context.
yeah i woulda preferred consumer and producer but i'd also just call tree-shaking dead code removal :shrug:
Before standardizing this, just build a common library that has the feature set similar to this. A polyfill without patching global objects, if you will. Migrate all frameworks to use this library. Ship it. Make them use what this proposal is intending so ship. See if it works for all of them in production, not just listing the frameworks in a proposal. We don't want to end up with an implementation that half of the frameworks listed effectively cannot use. Take your time iterating. If done, let's see if there are still benefits by bringing it into the browser and that justifies adding something to the language that will stay there forever.
Signals have been around for a long damn time, and are demonstrably good for performance already. The reason to get it in the language is that then the DOM can use it and the implementation can be even more performant. It would be super nice to be able to assign a function to a label and it Just Works™.
The most useful features have come from jQuery, which was used basically everywhere. Nowadays we have a bunch of frameworks with own set of features
@@saiv46exactly, signals are already in many frameworks and have proven their value. This just promotes it to the language level.
It looks like that's what they're doing, right?
WHat arer you, old?
Have u seen all the blahblah.JS c0ntribootor nnicknames at allz?
Wow, looks like Knockout. There it was called Observables. I loved these functions. They are very intuitiv. Great to see them as a tool in JS and thus in other frameworks.
Right! Anyway subscribing to ko observables could cause cycling deps. I wonder how they resolve or at least protect us from it
You know I had to pinch myself because someone was proposing a change to the spec instead of just creating yet another framework.
I thought methods like these were forbidden and everything new had to be done via a new framework in JS land. These brave guys really challenging the status quo and I hope it works for them.
/s
7:20 It's weird to me no one in chat pointed out the explanation of why this is valuable isn't complete. You could do the same with lambdas or function references that you call when you want to get the value, but the main difference with signals is the amount of computation. Signals are only computed once per update, they are not recomputed when you want to get the value, which is what's so powerful about them.
This explanation actually clarified something about signals for me. Thanks.
He literally said that shortly after.
@@tvujtatata Yes it was in the article. It wouldn't have escaped you as well that I was talking about chat at a timestep in the video as well, right?
The main benefit is in effects though. The effect will be re-run only if its sources change. If your effect is a React component, that means it will be rerendered only when necessary, without rerendering its parent or child components.
??? I mean that is the point its not an event implementation you ask for an update manually this is exactly what you often do in all kinds of systems with lambdas or function references. In the end similar to lambdas it makes it extremely hard to find out where things are happening
Fokcenk pipe operator, dear committee, pretty please.
Is it too much to ask? How much was it, 10 years?
Signals seemed cool until I used them in solidjs and did a production app. What I found out though is we had so many stale state issues and it really felt like working in backbonejs again with zombie views. This feels wayyyyyyyyy too overhyped. it's also created by people that did projects like mobx that nobody ever used either.
19:26 I'm not familiar with other signal implementations, but Preact signals have a peek() method that lets you read the value of the signal without subscribing to changes. This is similar to passing a function to setState() to use the current value, since you shouldn't be using the current value of "state" directly.
e.g.
signal.set(signal.peek() + 1)
vs
setState(prevState => prevState + 1)
You can do this in solid's signals too, through a couple of options, but it's a bit uglier IMHO.
It's untrack(() => ...) in Solid. Solid's signals are just two functions that you can call, not an object with methods like .get() .set()
@@reoseah Preact has untracked(() => ...) as well, but I haven't used it for basic state updates since its much more verbose
Something so convenient seems to go in the opposite direction to what the use of the subtle namespace is trying to imply.
So they want to bring Vue’s reactivity model to JS, sounds good to me 😅
10:30 wasn't sold until this point. this is actually super useful (from an optimization standpoint).
I do think it's cool how in almost every video you talk about the people, what they did, and what they are doing, as part of the context for what you're talking about. Bringing us up to speed on their "reputation" if you will, beyond just github stars.
Of course the downside is that we're not evaluating things solely based on their own merits, but the world really doesn't work like that, does it?
I don’t know about the actual implementation, but that’s sounds like vue.js
LMAO, I know web components aren't ideal in an environment where you can use frameworks. That said, I build and use web components daily, they work extremely well in a template based language system like shopify liquid themes. I see them as little islands of logic 😄. Although, behind the scenes I'm using solidjs which makes the whole process much better xD.
I've actually built an extremely complex set of web components used to render a dynamic js sidecart. The components work for rendering the data while having full control of styling the sidecart however you want. The best part is because we use SolidJs signals for both the cart and the web components graph, we can ensure fine grain updates within the sidecart's elements.
Sorry for the mini rant, I just want think they work really well under the right circumstances 😄.
Exactly, I'm also very fond of web components and use them a lot in a lot of projects.
Also I've seen some libraries for React like the Mux Client SDK and LiveKit that use web components under the hood and simply wrap their components in connectors to easily distribute their components across React, Svelte and others without having to rewrite their entire product.
Ayyy solid!!
If there’s anything I want in a codebase, its readability. I feel like this signals goes against this. Theres nothing that tells you what updates when and thus is waaaay too magic.
Do a find all references on the variable. It's trivial.
Sideeffects all over the place…
vuejs reactivity is hugely similar to this
We definitely need a more primitive-driven approach to web engineering application based on the main themes such as reactivity, rendering and networking.
Exciting proposal.
So signals works the same way as a spreadsheet.
All of the same seem to be achievable to me via RxJS. With RxJS you can do push via subject.next and you can do pull via observable.subscribe ... a UI component can subscribe/unsubscribe to an observable and will cause computation it builds on only when that observable is subscribed to. With RxJS you also get teardown support and a bunch of powerful operators. Composability is amazing with RxJS. Unfortunately it's too complicated for people who used to imperative code. Signals seem to be easier to use.
Technically you can achieve with Rx Subjects what Signals are trying to achieve but I think you will have to do all the optimizations yourself: manage subscriptions between streams, use distinctUntilChanged, combineLatest, avoid unnecessary computations by unsubscribing from upstream dependencies when a computed Subject does not have any subscribers.
@@andrei-ovisure, and it is okay to me
Question: how does isEven know that counter is its source? By that I mean how does it know to recalculate itself when counter becomes dirty?
In the definition I see no explicit definition of counter as source for isEven:
isEven =new Signal.Computed( ()=> !(counter.get()&1 )
I always kind of figured this was the job of the Proxy object that JS already has and Vue uses as part of its reactivity. Still, I'll take it.
yup, redux also uses it. when I roll some vanilla state management solution, I usually go with a proxy.
Mobx at the time was revolutionary. Bloated, quirky at early versions. Still blown up my apps complexity down to 1/3 of what it was before.
Exactly, I always loved MobX, used it from first public versions
This is LITERALLY how KnockoutJS works since 2010. Variables are all basically functions in which you can subscribe to including computed fields, which makes data model binding to the UI just insanely easy.
I moved onto React which meant a mindset shift to one way binding, looks like I need dust off those old parts of my brain once again.
23:44
elide verb
/ɪˈlaɪd/
elide something - to leave out the sound of part of a word when you are pronouncing it
“The ‘t’ in ‘often’ may be elided.”
🤓
Yes, this! Thank you
I guess my main question here is, how does it know? I mean, without React-style [dependency, arrays]? I get that a new language primitive could have the compiler examine the passed in function to see what's closured in and check if any of them are Signals, but a polyfill could never do that, so how could that work? The only way I can think of is to just evaluate everything every time and if the value hasn't changed, don't fire any of the events. But that won't really work for effects like x=> [x] because the new array won't equal the old one. I've had a look at the polyfill code and there is some tree management in there, but I didn't find anything that could really tell when something changes like this
It works the same way as it has in VueJS since at least 7 years and it's surprisingly simple. You run the function in the initial setup, and each call to `get()` registers the signal with the function. So for example effect(() => `console.log(myvalue.get()))` would initially log the value, and the call to "get()" would setup this lambda function to rerun the next time any call to `myvalue.set()` is being made (more or less). When it reruns the function it erases the tracking and registers all the get()'s again, that's why things like if-conditions still work. However, there are ways to also set up effects without running them first, in which case you would need to provide the signals as dependencies just like in Reacts use_effect.
@@Luxalpa oh man that's clever 😄
meanwhile i'm waiting for Temporal API for the last 2 years!
dude I'm not the only one.
After the fiasco of the Observable proposal, I don't have a lot of confidence that this will ever land. TC39 is a mess.
7:20 I’m the one who asked that question, and I’m not convinced that the “implementation performance” is a good enough reason. I’d argue JS implementation of such a high-level concept is comparable to the browser native one. I don’t particularly see opportunities for optimisations that the browser sees, where JS doesn’t.
I could accept an argument that it is done for interoperability between signals libraries, but debatably this could’ve been achieved by the common lib/adapters if desired. Don’t think there is much demand for interop. For it to be there, the signals ecosystem has to mature a bit.
I might have missed the argument given by theo live. I was hella eepy at 3am (eu gang rise up). Might’ve been chatting in the chat at that moment.
You would be surprised by how much Signals have matured. This effort to standardize stems from the fact that all frameworks have derived pretty much the same Signals implementation independently, the push-pull tainted graph. They do differ on how effects run and other details and the proposal accounts for that.
And one point about interop: even if they all agree on a single base signal lib, you need a single instance of the lib running for it to work (since it relies on a single call stack context to track subscriptions). This is challenging as it requires npm/yark/pnpm trickery with peerDependencies, bundler configuration, and/or manual setup.
My argument rests on interop not being desired enough feature. Don’t think it is. Can’t see many reasons why it would be. If it were, it is something that community can solve without tc39 standardization. Additionally, signals can be adapted between implementation, even if there is a perf penalty. I doubt that cross-signal-implementation calls are frequent enough to manifest perf issues.
As to other arguments I’ve encountered:
- Perf gains are likely insignificant
- Optimization opportunities are lacking
- Signals being in DOM doesn’t achieve much. Maybe observability of attributes. Can be done with MutationObserver (I’ll give you that it isn’t a particularly nice API)
Yea, it is doomer-like mentality and the “ooooh scare of change”, but maybe let’s not bloat JS even larger than it is. Look at where it has lead C++ to. But I guess either way, acceptance of the proposal won’t really affect me that much. I’ll gladly use JS signals if they are a part of library interface or they suit my needs (as opposed to reaching out for a 3rd party library).
You have every right to be excited by this addition. I am just not. Not sure it sits right with me.
There is a whole lot of optimization opportunities here. Implementing stuff like this in V8 or another JS runtime will drastically improve performance when you start to natively optimize dependency graphs and things like (de)serialization.
@@yapetthe interop goes beyond frontend frameworks. Signals being a first-class citizen could replace every kind of set+subscribe interface. I find Promises to be a good parallel here. Assuming you have been in this space long enough, would you rather still be using Bluebird.js or Q today? Did you imagine what the ecosystem would have looked like with native Promises back then? Could you imagine a JS world without native Promises today?
import { ref, computed } from "vue";
const counter = ref(0) ;
const isEven = computed(() => (counter.value & 1) == 0);
const parity = computed(() => isEven.value ? "even" : "odd");
but vanilla, and apparently fairly intelligent :D I need to see a good example of a server app, though.
Fine... I'll continue my Haskell journey tonight. Seriously how many more iterations of JS will it take just to solve 1 issue of STATE MANAGEMENT and PERFORMANT RENDERING.. It makes me sick.
Two thoughts:
1. We already had Observable as a proposal, which is essentially this. That flopped, how will this be different?
2. DOM values should be assignable to signals without an effect function, such that the value is auto-subscribed to the signal value.
Can anyone explain in 2 words how it builds dependency graph just from lambda function? It looks like magic for me
2 way reactivity can be a challenge when you're first hit with the circumstance, especially on the frontend where you come across large data sets and performance bottlenecks, but frankly it's something I've only found difficult in some frontend framework implementations. Vue and solid implement it well but a native implementation is welcome. This will only negatively impact those who have rigid mental models of unidirectional binding
The one thing that worries me is lists. Quite often, I do pass around lists of things, and arrays are - in JS land - quite often *weird*.
If I use a signal, and my computed value is [...someSignal.value.map(a => !a)] (Inverting some booleans for whatever reason), when is it considered equal? Is it considered equal if the object reference is the same? But that might be dangerous, because then I can push to an array, and, well, nothing has changed.
This is a problem reactive libraries like mobx try to solve, but it's actually not trivial. I can forsee quite a few footguns when working with arrays in either direction.
And then marking object hierarchies dirty because one of one nested value. Perf goes crash!
Regular arrays would presumably only be compared referentially. There is another proposal for structural equality. It adds records (which are essentially immutable objects) and tuples (immutable arrays). Look up "JavaScript Records & Tuples Proposal" if you're interested.
Signals is just a rebranding of reactive programming to make rxjs seem more friendly and approachable to devs.
how?
Rxjs is loaded with crap complexity, because it couldn't come up with smth js-native. Signals fixed that to some extent.
RXJS has everything it needs for the flexibility it requires for the complexity of the websites that use it.
In most sites you will only use map, and mergeMap to transform the values inside of Observables, fairly easy ideas to grasp.
But the core concept is very simple. Think of it like a Promise that can be triggered multiple times. It should have been added a long time ago, while leaving users/library creators to create operators for more complex uses.
RxJS is glitching by default, and that is terrible and leads to many bugs (at least in our production app it did), which are hard to debug and tedious to fix. Non-glitching signals are a *significant* improvement on Rx observables.
@@nUrnxvmhTEuU can you please tell us more about that "glitching"? I'm using RxJS for ~5years now and I had many problems with it... But EVERY time it was my mistake or missunderstoodment on some concepts/operators.
But I must agree that debugging it is very hard.. And also the documentation is... you know. :D
I've been writing "reactive" code especially for TCP/RPC servers for almost a decade using libs like rxjs and kefirjs. Nice of them to finally make it a first class citizen :P
Im not a pro, but this feels familiar with Legend state manager. Only they call it observables.
Having a sink that changes its value... isn't this like the computed refs in Vue?
This could do to FE frameworks what document.querySelector did to jquery
OpenJS needs to reject this proposal asap
How are signals different from the Observer Pattern?
Every time I try to leave JavaScript, something keeps pulling me back me back...
every time I get to the end of the list of reasons I don't like javascript, someone gives me a new one!
The return of Knockout.js (2010) and Bacon.js (2012)
So, its language support for knockout.js.
Finally!
6:53 what's wrong with this approach?
let x = 2;
const doubled = () => x * 2;
x = 4;
Doubled is recomputed every time you call it even when it doesn't need to
A closure isn't reactive. Yes, if you reevaluate the function you'll get the new result, but there's no mechanism to tell that you _should_ reeval because x changed. And there's no automatic memoization, avoiding the recompute when it isn't needed (which wouldn't be an issue in your example but would be massive if the computation involved i/o, for example).
@@PeteC62 well we can implement caching if the computation gets expensive.
@@pixelsam123 Instead of recomputing doubled, you walk the graph for dirty/clean and then decide whether to recompute.
There is a reason they like to use doubling a counter as an example. It's because the complexity factor goes up really fast when you try to use signals beyond very simple cases.
This is looks like an excellent functional solution to private state. The same problem why OO languages always give the advice: don't pick values off your data objects, pass the data objects
Definitely OVERHYPED MADNESS. thanks Theo.