Hooks, as I understand them, are just a way to add state (and lifecycle methods) to function components.
This FAQ answer:
In the longer term, we expect Hooks to be the primary way people write React components.
https://reactjs.org/docs/hooks-faq.html#should-i-use-hooks-classes-or-a-mix-of-both
and this documentation snippet:
Hooks let you split one component into smaller functions based on what pieces are related
https://reactjs.org/docs/hooks-intro.html
confuse me slightly as a React beginner.
It is as if I have to think about my app in terms of hooks rather than in terms of elements and components.
React didn't remove components, but the quote hints that hooks will replace
components as the primary source of code reuse.
Can one still talk about elements and components as primary abstractions in React?
The concept of components is not going away, it's just how they are written that is changing.
The second line you quoted
Hooks let you split one component into smaller functions based on what pieces are related
Is poorly worded in my opinion, and should rather say "Hooks let you split one class component into smaller functional components..."
So instead of having one monolithic class that handles all state and lifecycle logic in methods like componentDidMount, componentDidUpdate, you can split areas of concern and have smaller functional components that only care about things directly related to themselves.
Edit: This snippet from the hooks-intro doc might be helpful:
Hooks don’t replace your knowledge of React concepts. Instead, Hooks provide a more direct API to the React concepts you already know: props, state, context, refs, and lifecycle. As we will show later, Hooks also offer a new powerful way to combine them.
Currently, there are 2 ways of building components in React:
Class Component
Functional Component
You can check them here. The way you build it it's different. In case you approach the class component, that means that you need to work with the prototype of the object.
On the other side, if you choose to go as a functional component, that means that everything you request from React, is invoking a function, and not using the prototype at all. All this chaining from JS can slow down the performance, and that's why the React core team decided to go into pure functional direction: It can perform better, and it makes it even simpler to read it (once you get used to it).
Regarding the second quotation. It is a way to show more benefits of functional programming over classes. They are more flexible and can have a better composition for it.
One last addition: Approaching functional components doesn't mean you can ignore to learn class components. There's still a lot of apps with some legacy code. I would recommend learning both, and whenever you need to create new components, approach the functional component paradigm.
Related
Before react hooks, we called functional components to stateless components.
At that time it was really faster than class components but what about now?
Since we have react hooks, stateless components are no longer precise.
Does the functional components are faster than class components which runs same functions?
e.g.
In functional components,
I can handle state variables by using useState hook.
useEffect can represent componentDidMount, componentWillReceiveProps or some other lifecycle methods in Class component.
... ... ...
We have many other hook functions but which hooks will make my class components faster or lightweight?
Using React hooks will definitely reduce the amount of code you have to write in comparison to class based components.They are much easier to read and debug.
In sense of Performance , in class components :
Cleaning up and applying the effect after every render is task heavy,
and we might right run into issues or bugs.
so overall Hooks is a better option.
source
Both functional and class components in React offer the same functionality. You shouldn't miss anything when using any of the approaches and then you shouldn't differ in rendering performances.
In general, you write less code by using a functional component. This will be more understandable by your colleagues
According to the docs, there is no difference in terms of performance: https://reactjs.org/docs/hooks-faq.html#are-hooks-slow-because-of-creating-functions-in-render
I'm not really facing an issue, it's more like I'm wondering what is the best way I should use mobx with react. So here's my situation:
I'am fairly new to mobx but I've got years of experience using react (mostly with redux).
My new project is using mobx-state-tree alongside with mobx-react-lite in order to connect my components with the function observer wrapping the component. I've set up a root store with multiples stores in it.
I'm really enthusiastic about it for now but I would like some recommendations:
Should I use the containers logic which is pretty common with redux, which means I should only connect a "container" component who will handle the connection with my stores and spread it to its children ? Or should I connect directly with an observer as many components which needs to be provided with data from a store ?
Is the second option more optimized, technically speaking ? Is it still a good idea according to React philosophy ? What's YOUR opinion on this subject ?
Any answer would be really appreciated
Technically, you don't need container/presentation concept. You can use context, or localStore, or globalStore but it doesn't mean container/presentation not useful sometimes.
Mobx patches shouldComponentUpdate lifecycle, and basically optimizes components rendering for you.
mobx-react mentioned in their docs that the more components connected with observer, the better.
It's very common pattern to see shouldComponentUpdate with a bulky checks to avoid unnecessary renders. This isn't needed with MobX at all.
My opinion is that patterns change on monthly basis, so learning the general concepts can ease your transition from global store, local store, context, hooks and other api changes.
React component patterns also change overtime.
Use what you need and understand right now. If it won't matter in 5 years, don't spend more than 5 minutes to think about it. You can always do a fun refactor.
Further reading:
https://mobx.js.org/README.html
https://mobx-react.js.org
I'm starting a new React app and, seeing all the news in the ecosystem, I want to go slow and actually consider my choices, starting with just React/Webpack/Babel, and introducing more.
The first of these choices is whether to use Flux or not (more precisely, Redux, which looks great and seems to have won the flux wars). Here is where I am:
I understand Redux's benefits, summarized on SO by Dan Abramov. They look great, but I'd rather introduce things one step at a time.
In plain React, parent→child communication is done with props, and child→parent communication happens with callbacks. See Doc / Communicate Between Components, or SO / Child to parent communication in React (JSX) without flux, or this codeacademy Redux tutorial which starts out by saying "no need for Redux if you're fine with plain React and all your data in a root component".
Which looks just fine for my purpose...
... however, the sad part is that these callbacks have to be passed down the component chain, which becomes quickly tedious as the levels of nesting grow.
To solve this without introducing new dependencies, I found two articles (1: Andrew Farmer, 2: Hao Chuan) encouraging usage of the recently-introduced context feature of React.
→ Using context would let me expose my model-mutating callbacks to my child components. To me it doesn't sound like a horrible misuse: I wouldn't be passing model data, just references to functions for binding on event handlers.
Does it sound sane?
Any other plain-React suggestion for convenient child→parent communication?
Thanks.
Answering my own question after watching Dan Abramov's Getting Started with Redux series, which I warmly recommend.
Yes it looks like it's sane: Redux faced the very same problem and solved it with Context (at least initially, the implementation may have changed). It is implemented and packaged (among other things) in the react-redux bindings under the <Provider> component and the connect() function.
Initially, at the start of step 24 - Passing the Store Down Explicitly via Props , we have a Todo app with a Redux store available as top-level variable. This sucks (for 1. testability/mockability, 2. server rendering needing "a different store instance for every request because different requests have different data"), so the store is demoted from top-level variable to a root component prop.
As in my case, having to pass the store as prop to each component is annoying, so in 25 - Passing the Store Down Implicitly via Context, Dan demonstrates using Context to pass the Redux store to arbitrarily nested components.
It is followed by 26 - Passing the Store Down with <Provider> from react-redux, explaining how this was encapsulated in the react-redux bindings.
And 27 - Generating Containers with connect() from React Redux further encapsulates generation of a container component from a presentational component.
Personally, I find the question quite simple to answer, if you think about the way dependency injection in Angular works. In Angular you have your DOM, and then you have all those services, providers, factories, constants and whatnot, which are independent of the DOM structure and can be imported simply by mentioning their name when creating modules or controllers.
I liken the use of this.context to DI. The difference w.r.t to Angular is that instead of stating the dependencies using function parameter names, you use childContextTypes and instead of getting the dependencies as function arguments, you get them through this.context.
In this sense, asking the question whether passing model mutators through this.context is sane, boils down to whether it makes sense in Angular to register your model for dependency injection. I've never seen a problem with the latter, therefore I deduce that the former is also quite OK.
I'm not saying that it suits the spirit of the library, though. Dependency injection and in particular managing dependencies between injected component is not as explicit, so one may argue that it's not the React way. I leave this philosophical discussion to others.
Is it advisable or even possible to include a React element in a Redux store's state? Since it is a plain object describing "what should be drawn", I guess it should be safe, but still: any experience out there?
Why would I want to do such a thing? I'm writing an abstract React component capable of embedding other components, described elsewhere in the React tree. This would allow them, for instance, to escape from the physical boundaries of a hardware-accelerated, CSS-transformed DOM node, used for performance.
Yes - as with many other similar ideas, it's possible, but is absolutely an anti-pattern because it breaks the ability to do things like time-travel debugging (one of Redux's core selling points). See the Redux FAQ at http://redux.js.org/docs/FAQ.html#organizing-state-non-serializable for further details.
Now, keeping React component classes in a React component's internal state is different, and might be useful for cases like dynamically requiring a component and re-rendering once the implementation has been downloaded.
Tons of examples, describing React and Flux uses global variables: global Dispatcher, global Store and etc. Is there any way to proper inject dependencies to react components? There are some articles on the web describing how to use Dependency Injection component with React, but it based on undocumented weird feature called "Context" with unknown future.
Proper injection, for me, is classic constructor-based injection, without accessing global variables, without accessing static state and other.
It seems that I need to hook into component construction process (place, where new called). Can I do that? If so, how can I do that?
The most straightforward way to do dependency inversion with React is to simply pass any necessary dependencies as properties to the components that need them. Context is simply a way to pass the props down through child components, grandchild components, and so on implicitly without listing the prop on every component that may need it.
You'll find a lot of examples of this technique in the wild, and many make use of context and other niceties. React Redux is a popular one right now; pass a local variable to a top-level <Provider> component as a property, and it wires up the rest for you.
Dependency injection is less straightforward, and you'd probably need some kind of proper DI container or a DI library for JavaScript to do this nicely. Components aren't really instantiated, from the user's standpoint, the way other JS objects are, so doing "at instantiation time" injection of dependencies into components isn't how I'd approach the problem.