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ReactJS Interview Questions
The React Intl library makes internalization in React straightforward, with off-the-shelf components and an API that can handle everything from formatting strings, dates, and numbers, to pluralization. React Intl is part of FormatJS which provides bindings to React via its components and API.
It must have one JSX element present so that the task can be accomplished easily. Having more than one expression is not an issue but probably it will slow down the process. There are also chances of confusion with more than one expression if you are new to this technology.
Primarily, hooks in general enable the extraction and reuse of stateful logic that is common across multiple components without the burden of higher order components or render props. Hooks allow to easily manipulate the state of our functional component without needing to convert them into class components.
 
Hooks don’t work inside classes (because they let you use React without classes). By using them, we can totally avoid using lifecycle methods, such as componentDidMount, componentDidUpdate, componentWillUnmount. Instead, we will use built-in hooks like useEffect .
Explain what is the use of useState(0) there:
...
const [count, setCounter] = useState(0);
const [moreStuff, setMoreStuff] = useState(...);
...

const setCount = () => {
    setCounter(count + 1);
    setMoreStuff(...);
    ...
};

useState is one of build-in react hooks. useState(0) returns a tuple where the first parameter count is the current state of the counter and setCounter is the method that will allow us to update the counter's state.

We can use the setCounter method to update the state of count anywhere - In this case we are using it inside of the setCount function where we can do more things; the idea with hooks is that we are able to keep our code more functional and avoid class based components if not desired/needed.

ReactTestUtils are provided in the with-addons package and allow you to perform actions against a simulated DOM for the purpose of unit testing.
Jest is a JavaScript unit testing framework created by Facebook based on Jasmine and provides automated mock creation and a jsdom environment. It's often used for testing components.
React is a JavaScript library, supporting both front end web and being run on the server, for building user interfaces and web applications.
 
React Native is a mobile framework that compiles to native app components, allowing you to build native mobile applications (iOS, Android, and Windows) in JavaScript that allows you to use React to build your components, and implements React under the hood.
Relay is a JavaScript framework for providing a data layer and client-server communication to web applications using the React view layer.
Controlled component is more advisable to use as it is easier to implement forms in it. In this, form data are handled by React components. A controlled input accepts values as props and callbacks to change that value.
 
uncontrolled component is a substitute for controlled components. Here form data is handled by DOM itself. In uncomfortable components, the ref can be used to get the form values from DOM.
You can utilize redux-thud middleware which enables you to characterize async activities.
 
How about we take a case of bringing explicit record as an AJAX call utilizing get API:
trade work fetchAccount(id) {
 return dispatch => {
   dispatch(setLoadingAccountState())/Show a stacking spinner
   get(‘/account/${id}’, (reaction) => {
   dispatch(doneFetchingAccount())/Hide stacking spinner
   on the off chance that (response.status === 200) {
   dispatch(setAccount(response.json))/Use an ordinary capacity to set the got state
   } else {
     dispatch(someError)
    }
 })
 }
}
work setAccount(data) {
return { type: ‘SET_Account’, information: information }
}​