reselect VS Immer

Reselect solves this problem by memorizing the values and only passing what’s necessary.

reselect : Selector library to optimize your store access

Reselect documentation:

Reselect is a library for creating memoized “selector” functions. Commonly used with Redux, to slice state and provide just the necessary subtree to a React component.

For the redux part, you need to use two hooks. The first one is for sending data and that is useDispatch and for getting data from redux is useSelector. This link will help you a lot. The only that left is Reselect concept. The thing with redux is that when you update one state inside of the redux store the whole thing updates itself so basically it may cause you to re-render your components. Reselect will prevent that but it's a little bit advanced topic whenever you were comfortable enough with redux I suggest you learn to use reselect. Other than these Really good work with the project.😉👍 welcome to the community. 😁

At my current client we're working on having a frontend architecture for writing SPAs in JavaScript similar to re-frame's one: an event-driven bus with effects and coeffects for state management[1] (commands) and subscriptions using reselect's selectors (queries).

Heh, it's amusing to see Redux Toolkit referenced here. I'm one of the two main RTK maintainers. My co-maintainer Lenz Weber is responsible for most of our TS type wizardry.

Agreed that writing TS types for libs can be a pain. I actually did a talk recently on "Lessons Learned Maintaining TS Libraries" [0], where I talked about some of the techniques we used, and some possible TS changes that would be helpful for us as maintainers.

As one recent example, TS made a change in a 4.8 pre-alpha that broke RTK's `createSlice` types. Lenz tried to come up with a fix, couldn't, and had to add a workaround to check what TS version is being used and specifically use an altered type. Since there _isn't_ a good way to know what TS version is being used, Lenz resorted to hacking together a new package that abuses the `typesVersions` property to define a different TS type for _every_ TS major+minor version combo, and then used that to decide what the RTK type should look like conditionally [1].

Another pain point is debugging type transformations. I reworked the Reselect types in 4.1.x to do a much better job of inferring the argument types for the final selector, based on the intersection of all the input selector arguments. This ended up as a monstrous type that does a types-level map + transpose + intersection [2]. It took me weeks to get this working right, and I frequently had to break it down into multiple small intermediate types to see how TS was processing each step.

I know that someone on Twitter was recently working on an alternate TS type-checker based on bytecode, and they said they had some kind of a working types-level debugger [3]. Having something like that officially, where I could see each step of how TS was transforming the types, would be _hugely_ valuable.

There's a couple folks like AndaristRake who are able to dig into the internals of the TS compiler itself to trace how it's interpreting the types. I definitely don't have that ability :)

[0] https://blog.isquaredsoftware.com/2022/05/presentations-ts-l...

[1] https://github.com/reduxjs/redux-toolkit/pull/2547

[2] https://github.com/reduxjs/reselect/blob/v4.1.5/src/types.ts...

[3] https://twitter.com/MarcJSchmidt/status/1539787500788613120

We do a _lot_ of this in the Redux library repos (examples: [0] [1] [2] ). We have some incredibly complicated types in our libraries, and we have a bunch of type tests to confirm expected behavior.

Generally, these can just be some TS files that get compiled with `tsc`, but it helps to have a bunch of type-level assertions about expected types.

I actually recently gave a talk on "Lessons Learned Maintaining TS Libraries" [3], and had a couple slides covering the value of type tests and some techniques.

[0] Redux Toolkit's `createSlice`: https://github.com/reduxjs/redux-toolkit/blob/9e24958e6146cd...

[1] Reselect's `createSelector`: https://github.com/reduxjs/reselect/blob/f53eb41d76da0ea5897...

[2] React-Redux's `connect`: https://github.com/reduxjs/react-redux/blob/720f0ba79236cdc3...

[3] https://blog.isquaredsoftware.com/2022/05/presentations-ts-l...

While Reselect has always been a separate library from Redux itself, it's in our Github org. The previous maintainer had to stop working on it, so a couple months ago we did some major updates to Reselect. Reselect 4.1.x has huge improvements to its TS types for better inference, and adds a new set of customization options like cache sizes > 1.

Fourth, Use Reselect / Re-reselect in Redux to Avoid Frequent Re-render. Reselect is a library for building memoized selectors that is commonly used for redux.

I heard that immutability libraries like immer.js [0] help with this. Anyone go this way and had good success? Is this 'the way'?

[0]: https://immerjs.github.io/immer/

But is immer really the ultimate answer? The performance problem of immer is more prominent in large arrays and deep-level object scenarios. See this issue description, many authors in the community began to try to make breakthroughs, and noticed that structura and mutative, I found that it is indeed many times faster than immer as they said, but it still fails to solve the problem of both fast speed and good development experience. I will analyze the two issues in detail below.

I like immer for this kind of thing: https://github.com/immerjs/immer

It gives you immutable updates without getting bogged down in FP abstractions.

If you're trying to make things actually immutable, Object.freeze and deep copies can clutter things up pretty good, have you considered using something like immer? (https://immerjs.github.io/immer/)

If you want to set up from Context, Zustand is your best bet. It offers an extremely simple API that lets you create a store with values and functions. Then, you can access that store from anywhere in your application to read and write values. Reactivity included! If you want to store nested object data in your store, consider using Immer alongside Zustand to easily change nested state.

immer

I don't know about immer, do you mean the JavaScript library immer?

Deep cloning is almost never the right answer - you'll end up copying _too many_ object references, which is extra work, and that can also lead to unnecessary re-renders depending on what your components are trying to do.

A correct immutable update is more like a "nested shallow update", copying all levels of nested keypaths leading to the actual value you want to update.

If you prefer to avoid writing those immutable operations by hand, Immer is a fantastic tool for simplifying the code by using "mutating" syntax that gets turned into a safe and correct immutable update:

- https://immerjs.github.io/immer/

- https://beta.reactjs.org/learn/updating-objects-in-state#wri...

We even use Immer by default in Redux Toolkit:

- https://redux-toolkit.js.org/usage/immer-reducers