[bloomca]

React is not pure at all, and has a few gotchas related to updates. That being said, the JSX and composability of it is unmatched and I think the main reason React "won".

I think a logical continuation of this model is something like Solid.js, where there is no concept of re-rendering, just atomic DOM updates when observables change their values, but somehow this approach didn't get critical traction.

[embedding-shape]

Nothing of value is 100% "pure", eventually you are gonna need to draw something to the screen, so trying to reach that sort of utopia seems futile.

With that said, the "mental model" of React, or maybe the focus, is "pure" where it matters, namely that you have data, pass it through a function, and you get a view/UI, and if you pass the same data, you get the same UI, regardless of what happened before.

When it appeared, was very different from us web developers were used to, where sometimes the DOM even was our data store, and mutation was the name of the game.

So when people say "React is pure", I don't think they're talking about internally, or "100% pure", just that the mental model you need to adjust to is that the UI gets created from (mostly) pure functions.

Of course, this all breaks down once the frontend application actually runs in a browser, but that doesn't mean it isn't valuable for the developer as things gets a lot simpler.

Not disagreeing with you in the end I guess, just clarifying for those who might not be familiar with React, and get confused when some people say it's pure, while others don't. Both are right :)

[valenterry]

Nope, that is precisely what pure functional programming is about: to turn actions like "draw something to the screen" into regular values that you can store into a variable, pass around, return from a function and so on.

It's not an utopia. It will eventually happen and it will replace how react.js currently works. effect.website will probably be the foundation.

[mpweiher]

> React is not pure at all

Yeah, my pull request to make the documentation honest about this has languished.

https://github.com/reactjs/react-basic/pull/12

[dmix]

> I think a logical continuation of this model is something like Solid.js, where there is no concept of re-rendering, just atomic DOM updates when observables change their values,

I believe Vue is going in that direction https://www.vuemastery.com/blog/the-future-of-vue-vapor-mode...

[greener_grass]

It exists, but as a Haskell library called Reflex. This is why it didn't gain traction ;)

[kybernetikos]

Knockout js worked something like that. There are complexities with the observable approach though, especially around batched updates and avoiding update loops.

[embedding-shape]

Not to mention debugging Knockout.js applications was as complex as debugging jQuery applications, mutable state that can be changed from anywhere and from any direction makes it really hard to see what's going on. React was a breadth of fresh air when it appeared.