RFC: Intent to Ship React 18
github.com
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At the same time there's a huge amount of React code at this point. It would be an interesting experiment to try to compile React code to really reactive code that doesn't need virtual DOM.
I haven’t built anything big with it yet but I like what I see so far!
Svelte might have that all reasoned out though, in which case the harder separation of logic and view is the only stickler for me, and transpiling JSX into svelte would be interesting to see.
With hooks at least I am able to have a mental model around what happens when I call a change function since it flows top down (instead of bottom up).
So do hooks. Suddenly regular function calls can't be put in if statements or require "dependency lists" to make them work properly.
Also you're just just passing a callback function to React and then giving it some pointers to data used as part of the conditional on when it should run.
Like it's janky and reaches through layers but it's not up and rewriting your code.
In Javascript, "just iterables" can be put in conditional statements, and they don't cause the outer function to be called again.
> Also you're just just
Ah yes. That "just" again
Edit:
> just passing a callback function to React and then giving it some pointers to data
Thing is, in plain JavaScript if it was a callback function, it could be called anything and live anywhere. However, these functions have to be named with a `use` prefix and have limitations on how they can be called.
- These are "just function calls"
- Except they are "iterators"
- Except if you have them in a conditional, you must provide an `else` branch so that `next` is called the same number of times
None of this is in the semantics of the language where I don't have to provide an else branch to an iterator, and function calls are not iterators ;)
* React stores the state for your hooks in a list which is iterable.
* useBlah is just a normal function that internally calls next() on that list to get the next hook state which is why order matters.
* React checks that the iteratior on the list is at the end to see if you’ve consumed all the hooks and throws an error if not because it’s indicative of a bug in your code.
Like at this point the only thing I can recommend is try writing a toy implementation of hooks and see that they’re not magic, they’re just normal JS, and that the restrictions flow naturally from the implementation.
Like why do you want so bad for hooks to be weird?
you keep showing isn't a normal function :)
> Like why do you want so bad for hooks to be weird?
I don't want them to be weird. They are weird already. https://news.ycombinator.com/item?id=30801466
it = ["hello", "world", "foo", "bar"]
shouldbehello = next(it)
shouldbeworld = next(it)
if sometimes_true_sometimes_false:
shouldbefoo = next(it)
# if the conditional is false this will be foo, oops.
shouldbebar = next(it)
def react_to_stuff(func, var):
orig = var.copy()
def monitor():
while True:
sleep 2
if var != orig:
orig = var.copy()
func(var)
t = Thread(target=monitor)
t.start()
stuff = "Hello"
react_to_stuff(lambda x: print(x), stuff)On "it's iterators actually", I have a response to a sibling comment here: https://news.ycombinator.com/item?id=30799543
So are hooks. The fact that you can't put regular function calls (which hooks look like) in an if statement, or have to provide custom "dependency lists" to some of them, or that data returned from them suddenly re-renders (aka calls again) the function they are in tells you that this is no longer regular Javascript.
I’ve helped teams pilot out of own-the-world frameworks like Backbone and Rails before (both of which substantially distort the runtime they’re embedded in); but it was much harder to deal with Backbone + Coffeescript together. For Backbone w/ vanilla JS or Rails, we could use standard static analysis tools, Coffeescript added a big extra wrinkle to our migration.
There's a fundamental difference between a framework that takes your code and does weird things with it, vs a framework that rewrites the semantics of your code out from under you.
- They're tied to the lifecycle of the component, so they must reach "up" into whatever just called our component function.
- They do not like being moved about/conditionally executed, so hook's likely use an array for metadata storage and position rather than needing explicit "hook keys".
I've no clue what svelte does behind the scenes, much the same way as I can't reckon what WASM or assembly do. So I guess I just have to blindly trust the compiler?
I think they are actually _more_ explicit than classes about how the state is stored. IMO `this` in class based components isn't as straightforward (e.g. https://overreacted.io/why-do-we-write-super-props/)
There’s some real overhead of React’s virtual DOM.
The VDOM definitely carried overhead in my case, but it was easy to profile and optimize (with the React tools). In many cases, reflowing the sheer size of the DOM we were generating was a bigger bottleneck than the time it took React to render it in the first place
I'm really curious what was going on in your app
Can a better design help to mitigate those issues? Sure. But I don't like having to wonder whether it was my own design, or if it's something internal to the library.
This is the part I thought I was bizarre:
> The React profiler wasn’t able to show any latency in my render functions and using the browser profiler I saw that all time was spent somewhere inside React’s internal
Svelte avoids this by magically not doing the unnecessary work. That doesn't mean it's faster, it just means your design needs to make different kinds of considerations.
React also gives you great tools to avoid and remediate this (memoization wrappers, the dev tools highlight elements that rerender, linters that check you're using hooks correctly), so it's really hard to say that this is a slowness that's endemic to the vdom.
I thought React and React-DOM were separate?
Still the best choice for huge, corporate frontend projects.
Really looking forward to server components.
Looking back at the JS side where the types don't bite, there's a library for everything, and the logos are really good, what we end up with are a lot of first year, or first three year contributions to the ecosystem, so a lot of patterns and algorithms are wisdom lost and aren't present, a lot of libraries are good but not perfect, and there is really no incentive to really dive in and become an expert on a given framework like react, because any day the community might decide, "It's VUE time now" or some such other technology, and suddenly you're the guy using Gulp and Angular on a busted 2021 macbook at the hackathon and people are addressing you as "sir"
There is no incentive to be "the react guy" when it comes to JS ecosystem, that 15 mins is quick.
I don't really disagree with anything you said, except to point out that a lot of the current crop of web devs have never experienced what it is to build an app without any abstraction such as React, and quite understandably have no idea what problems it is doing for them.
I do know that since hopping onto react with all of that ~baggage~ context, I have never wanted to program UIs with a different model. It is true that hooks introduce a layer of abstraction that is sometimes difficult to reason about, but IMO they boil down the problems we faced with class components/lifecycle/server rendering gotchas, and put them front and center - forcing you to confront and fix them rather than settling for a solution that works 99% of the time.
This is true. A lot of those struggles that the earlier people established, the patterns and best uses, those are lessons learned the hard way, and the impact on generation 2 is often much less because that wasn't a problem that needed to be overcome.
People understand how to use hooks, but I don't think many people understand them.
What do you mean? If you're asking if they can and do use useEffect for its intended purpose regularly and don't run into edge cases any more often than with any other coding pattern, then yeah, they understand how useEffect actually works. If you're asking if they have a deep technical understanding of how hooks are implemented in the React library and every potential "gotcha" they might ever run into, then sure, probably not, but the same goes for every basic pattern used in any programming language.
Honestly, I would say 90% of professional engineers don't understand how these reactivity models actually work under the hood, and that is okay because it's not strictly necessary to get the job done.
That being said, if I ever had a candidate that is in that remaining % of people who not only know how to use the technology, but what it's doing under the hood (and as a bonus, the benefits and drawbacks of a given approach), it would be an enthusiastic two thumbs up from me.
s/how/why/
There are many reasonable criticisms of hooks, like 1) some people have a strong personal distaste for them, 2) some educators say they're difficult to teach to newcomers, and 3) many people who use them don't have a deep understanding of how they work and how to handle some of the "gotchas." But none of them lead me to conclude that people "still don't understand how to use them."
Simplicity is key here.
I think the concept of hooks is fine, but JS/TS is an insane language and requires an enormous amount of discipline to write.
One of the nicest things about hooks + functional components is how much easier it is to refactor. With class based components, nested state and lifecycle behavior made it sometimes difficult to break down complex components.
But I feel like with functional components and hooks, refactoring into logical subcomponents is a breeze.
Now...that "little" it's-not-a-framework-it's-a-library whose scope is supposed to be confined to just the "view" part of MVC (by which I mean: "React") is inserting it's tentacles (along with a quirky architecture and proven to be error-prone coding patterns, cough, hooks) into the _model_. And it's already corrupted (at least partially) the "controller" part of MVC through React's synthetic events. But hey, at least React doesn't have one of those nasty DSLs, like those Web application libraries/frameworks that use a simple templating syntax on top of plain HTML. Oh wait, JSX is a . . . DSL, and a pretty nasty one at that, given that it's ever-confusing as where JavaScript syntax is legal vs. where HTML is legal; and, oh yeah, the bracketing rules fight each other all day long. But hey, what do you expect when you combine the careful syntax design of JavaScript with the terseness and simplicity of, umm, XML?
So now React's about to ship version 18, which provides functionality which is _roughly comparable_ to version, ummmm, _3_ of Vue.js??? Well, let's see, the React folks have _already, in just a few years_ deprecated (as best I remember): Class-based components, Mix-Ins, Higher-Order Components (HOCs) . . . what's next--let's deprecate hooks?, in favor of, oh I don't know, . . . .sheesh!
Please just STOP now. Wind up the company and give the money back to the investors. (Yes, I know that React is Meta-sponsored FOSS; that last comment was just pure snark...)
On a personal note, I'd like to rebut a comment made elsewhere on this page by '0des': "The JS ecosystem skews younger, not in age, but in years programming." As a counter point, I've been doing Web application development since the early 2000s. Yes, I've worked with Web app. libraries and frameworks that many Front End Developers have not used, or maybe even heard of. Backbone, sure. How about GWT? Or maybe ES4, by which I mean Adobe Flex? How about TIBCO General Interface?
Have you heard of Vitamin C? Trick question--it's not a Web view/app library or even a GUI library--it's a TUI library from the late 1980s/early 1990. Which is to say, I shipped my first front-end code in 1984. And even though I also do full-stack coding, and UX stuff, most of my career has been in front-end coding, both desktop applications AND web applications. Which is to say, at least anecdotally (and possibly egotistically), that I think that I have a pretty well-informed opinions on what makes a good front-end framework.
React impresses me not-at-all; except in a: look-at-me-I'm-so-clever way--now new-and-improved--with extra _functional_ goodness(TM). Conversely, I've scaled Vue.js and Flex applications with so little stress (but with tremendous productivity) that I could laser-focus on the feature set, and on delivering a top-notch user experience.
I need a Web application framework (or at least a View/Rendering mgmt. library) that has these things: - Strong support for UI componentization - CSS isolation - Clean, orthogonal, basic abstractions for change handling and local state management - Tractable to scale - M, V, and logic aspects are (easy to) decouple
Also very useful: - One-way data binding - Robust, but low-ceremony approach to centralized state management - Flexible, but type-safe way to marshall/un-marshall data going out/coming in
I'm open to assessing other/new libraries, but the last five years of my career have almost wholly involved coding with Vue.js or React. HOWEVER, I only learned React because I thought that the job market demanded it--not because I ever thought that it was a great library! I'm open to learning other/newer libraries, if they are promising enough, AND if if looks like there is job market demand for them. But the previous version of Vue.js already gave me all five of the needs that I mentioned, above; plus one-way and pseudo two-way data binding. So all I need is Vuex5/Pinia for state management (but I'd be willing to also look at something like a Vue-specific alternative to Tanner's React Query), and there is an increasing wealth of solutions for data marshalling with or without GraphQL.
So, bottom line, in my current job search I am taking a hard line: if React is required, then I'm out. And if you're already using Vue, or are at least open to modernizing your current front-end coding approeach, then I'm interested.
> Now...that "little" it's-not-a-framework-it's-a-library whose scope is supposed to be confined to just the "view" part of MVC (by which I mean: "React") is inserting it's tentacles [...] into the _model_.
useSyncExternalStore doesn't care about what you do in your model. it's for connecting your view to your model in a way that doesn't give you inconsistent states when concurrent-rendering-funkiness happens.
you could even say that useSyncExternalStore exists because React maintainers want people to be able to use whatever state-manager they want (instead of useState/useReducer/whatever) -- uSES was necessary to enable that in 18.