React Redux Interview Questions
Congratulations on being shortlisted for the interview! Now your focus should be on cracking your interview, before we dig into the redux interview questions; we want to tell a bit about Redux and its scope. Redux works as an open-source JavaScript library that is used for managing the application state. It is written in JavaScript and it was created by Dan Abramov and Andrew Clark. Also, the scope of redux is increasing day by day as it makes the state changes in apps more predictable and hence results in the easy testing of the app.
We put together the list of all the important react redux interview questions for all the career stages (fresher, intermediate, and professional experts). These questions are going to work best for quick browsing just before the interview.
Most Frequently Asked Redux Interview Questions
Instead of downsides, there are few compromises of using Redux over Flux that is listed below:
- You need to learn the avoiding of mutations: Flux is un-opinionated about mutating the data, however, Redux does not like mutations, and most of the packages which are complementary to Redux should never alter the state.
- You have to carefully pick your packages: While Flux principle does not try to solve the problems such as undo or redo, persistence, or the forms where Redux has extension points like store enhancers and middleware.
- No nice Flow integration yet: Flux allows you to do impressive static type checks that Redux does not support yet.
The reducers in redux are the pure functions that take the previous state and an action, and then it returns to the next state.
(previousState, action) => newState
It is known as the reducer because they are the type of function that would pass to Array.prototype.reduce(reducer, ?initialValue). It is very essential to ensure that the reducer stays pure.
To maintain this, there are few things that you should never do inside the reducer:
- Modify its argument
- Make sure not to perform some side effects such as routing transitions and API calls
- Call non-pure functions, e.g. Date.now() or Math.random().
const initialState = { value: 0 }
function counterReducer(state = initialState, action) {
// Check to see if the reducer cares about this action
if (action.type === 'counter/incremented') {
// If so, make a copy of `state`
return {
...state,
// and update the copy with the new value
value: state.value + 1
}
}
// otherwise return the existing state unchanged
return state
}
When you use an IDE, the constants allow you to find all the usages of specific functionality across the project. It also prevents you from making silly mistakes which are usually caused by typos; in that case, you will receive a Reference Error immediately.
Redux Thunk middleware is something that allows the developers to write the action creators that return functions, not actions. The redux-thunk can also be used for postponing the dispatch of action or to dispatch just if a specific condition is met. The inner function gets the “store” methods dispatch and getState() as the parameters.
| Relay | Redux |
|---|---|
| It only manages the state that originated from the server. | Redux manages and handles all the states of the application. |
| Relay caches and optimizes the data. | Redux does not handle data fetching; however, this can be done manually. |
Conclusion
Try to share or write the code wherever possible as it will show your technical skills. That’s it, you are all set for your interview. Now, you only need to practice these react redux interview questions again and again so that you can build confidence in yourself and create a positive impression on the interviewer with your perfect answers.