This question already has answers here:
When to use ES6 class based React components vs. functional ES6 React components?
(7 answers)
Closed 1 year ago.
Before React16, class components were used over functional components whenever there is a need to use state or lifecycle methods in your component.
In the latest release react introduced Hooks and Effects using which we can use state and lifecycle methods inside our functional components.
So is there any reason why still the class components exists? Is there any cases we still have to choose class components over functional
Here you can see the cases where you will need class components
The most common case where you will need class components is if you want to make an ErrorBoundary, you will need a class component because you can't implement componentDidCatch with hooks... yet!
Related
I am new to React and learning it. From this link:
There are mainly two components in React:
Functional Components also known as Stateless component
Class Component also known as Stateful component
and it seems that functional components are the rage these days e.g., I inherited some code and it uses functional components everywhere. The same article is then saying:
... a functional component is just a plain JavaScript function, we
cannot use setState() method inside component. That’s why they also
get called functional stateless components. ... useState can be used
to store state in a functional component.
and I do see tons of code using useState in functional components to modify state. Can someone explain this to me?
Answering my own question.
Functional components were referred to as stateless components but its no longer correct to think of them as stateless. This link from official documentation explains it:
You might have previously known these as “stateless components”. We’re
now introducing the ability to use React state from these, so we
prefer the name “function components”.
To answer the second part of the question, functional components are indeed the rage these days because that's the official guidance and recommendation. From this page:
In the longer term, we expect Hooks to be the primary way people write
React components.
Also see this page for some background and comparison of class components vs. functional components.
Can we build whole react app using functional component or class based components are compulsory for building stateful components?
You can use functional components to build the whole app too!
With the help of React Hooks, state management has been made possible with functional components too and for any new projects, its a recommended way to go.
Since React 16.8, they've introduced react hooks. So now you can build your whole application with functional components using props based approach and with hooks you can have everything that a class based component provides.
So it's your decision with which you need to go. But if you consider testing with 100% factor then functional components with hooks are the best option to opt.
I came to realised that hooks on functional components could do what class component could do without the class component lifecycle.
Is there any example where we need to and have to use a class component instead of a functional component?
Thanks
ErrorBoundaries can only be implemented with class components.
As per the hooks FAQ
There are no Hook equivalents to the uncommon
getSnapshotBeforeUpdate, getDerivedStateFromError and
componentDidCatch lifecycles yet.
In order to use the above lifecycles you would need to use class components
Apart from this all other useCases can be implemented with functional components with hooks
This question already has answers here:
When to use ES6 class based React components vs. functional ES6 React components?
(7 answers)
Closed 1 year ago.
Are class components being abandoned?
I see that in several libraries examples have function components as a priority.
Especially React Navigation.
Likewise, React itself with Hooks only makes them available for function components.
The main question is: Why are function components being so prioritized?
No, i think Class Components won't be abandoned today. Maybe in future.
They aren't lightweight as Functional Components can be, but i see a lot projects on community using Class Components.
However, here we have some reasons why the community is supporting the Functional Components approach:
Class Components requires more code but will also give you some benefits which you will see later on (the transpiled code by Babel will be larger too)
A functional component is just a plain JavaScript function which accepts props as an argument and returns a React element.
Functional component are much easier to read and test because they are plain JavaScript functions (less code).
The React team mentioned that there may be a performance boost for functional component in future React version
See this answer: https://stackoverflow.com/a/49613435/4119452
More info: https://www.twilio.com/blog/react-choose-functional-components
now a days, class components and functional components are almost same. In functional component Hooks were not introduced before and to make equivalent of class component, functional component gets new hooks like useState, useRef, useMemo which are equivalent to this.state, React.createRef and PureComponent.
Moreover, componentDidUpdate on class component can be used useEffect on functional component.
More details please check
Functional Components vs Class Components in React and React JS — Understanding Functional & Class Components
Hooks-first approach [Update 2020]
React team is currently re-building docs with Hooks-first approach which should be a preference for all new features and apps:
In future, is there any chance that Class Components becoming deprecated?
Class components are going to be around for years to come—for example,
there are tens of thousands in production at Facebook already.
However, we do recommend that new apps be built with function
components and Hooks, which is why we want those docs front and
center.
https://github.com/reactjs/reactjs.org/issues/3308
This question already has answers here:
Redux Presentational Components Vs Container Component
(3 answers)
Closed 5 years ago.
When should we use presentational component and when should we use container component?
Prensentational components (or dumb components) normally are used on to create some UI they don't care about how the data is loaded or mutated, they don't have any logic inside(if they have is via props), often they are created as functional components unless they need some state or lifecycle methods.
Containers component (or smart components) They are a charge of carrying data to components (presentational or other containers) instead of passing props down and down. If you are using react-redux every component that you wrap with connect and pass a mapStateToProps function are considered Containers.
Check this post by Dan Abramov, he explains in more detail this topic
https://medium.com/#dan_abramov/smart-and-dumb-components-7ca2f9a7c7d0
Presentational - no state, have no dependencies on the rest of the
app, handle how things look
Container - usually has state, call redux actions, handle how things work
Full comparison here: Presentational and Container Components