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In this article, the editor introduces in detail "what are the Redux interview questions and answers", the content is detailed, the steps are clear, and the details are handled properly. I hope this "Redux interview questions and answers" article can help you solve your doubts.

1. What is Redux?

Redux is one of the most popular front-end development libraries in the market today.

It is a predictable state container for JavaScript applications and is used for state management of the entire application.

Applications developed with Redux are easy to test, can run in different environments, and exhibit consistent behavior.

2. What are the three principles followed by Redux?

Single source of fact: the state of the entire application is stored in an object / state tree in a single store.

A single state tree makes it easier to track changes over time and to debug or check applications.

State is read-only: the only way to change state is to trigger an action.

An action is a normal JS object that describes a change.

Just as state is the smallest representation of data, action is the smallest representation of data changes.

Make changes using pure functions: in order to specify how to convert through operations.

3. Middleware of Redux

The middleware provides a mode of third-party plug-ins to customize the process of intercepting action-> reducer. Change to action-> middlewares-> reducer. This mechanism allows us to change the data flow to achieve functions such as asynchronous action, action filtering, log output, exception reporting and so on.

Common middleware:

Redux-logger: provides log output

Redux-thunk: handling asynchronous operations

Redux-promise: handles asynchronous operations. The return value of actionCreator is promise.

4. What are the shortcomings of Redux?

The data required by a component must be passed by the parent component and cannot be taken directly from the store as in flux.

When a component-related data is updated, even if the parent component does not need to use the component, the parent component will still re-render, which may have an efficiency impact, or may need to write a complex shouldComponentUpdate to determine.

5. How do you understand "single data source"?

Redux uses "Store" to store the entire state of the application in one place.

Therefore, the state of all components is stored in storage, and they receive updates from the storage itself.

A single state tree makes it easier to track changes over time and to debug or check applications.

6. List the components of Redux

Redux consists of the following components:

Action- it is an object that describes what happened.

It is a place that determines how the state changes.

Storage-the state / object tree of the entire application is saved in storage.

View-simply displays the data provided by the storage.

8. How to define an operation in Redux?

An operation in React must have a type property, which indicates the type of operation being performed.

They must be defined as a string constant, and you can add more attributes to it.

In Redux, operations are created using a function called Action creator.

9. Analyze the function of Reducer

Reducer is a pure function that specifies how the state of the application changes with the operation.

Reduce works by getting previous states and actions, and then returns a new state.

It determines which type of update needs to be performed based on the type of operation, and then returns the new value.

If no work is required, it will return to its previous state.

10. What is the meaning of Store storage in Redux?

The store is a JavaScript object that saves the state of the application and provides helper methods to access the state, dispatch operations, and register listeners.

The entire state / object tree of the application is saved in a single store.

Therefore, Redux is very simple and predictable.

We can pass the middleware to the storage to process the data and keep logs of various operations that change the storage state. All operations return a new state through reduce.

11. What are the advantages of Redux?

The advantages of Redux are:

Predictability of results-because there is always a real source, storage, there is no confusion about how to synchronize the current state with operations and other parts of the application.

Maintainability-code becomes easier to maintain through predictable results and strict structure.

Server-side rendering-simply pass the storage created on the server to the client.

This is useful for initial rendering and provides a better user experience because it optimizes the performance of the application.

Developer tools-developers can track everything that happens in an application in real time, from actions to state changes.

Communities and ecosystems-there is a huge community behind Redux, which makes it easier to use.

A large talent community has contributed to the improvement and development of various applications of the library.

Easy to test-Redux's code is mainly small, pure, and isolated functions.

This makes the code testable and independent.

Organization-Redux defines exactly how the code is organized, which makes the code more consistent and easier to use by the team.

What are the benefits of Redux?

Maintain ability, due to the strict code style requirements, so the maintainability is relatively strong.

Organization, the code is well organized, so it's actually relatively easy to do the work.

Server rendering. The store created on the server side is forwarded to the client.

Developer tools. Convenient and powerful developer tools provide convenience for debugging and real-time development.

Ease of testing. Small functions are basically used to do only one thing, which makes the whole test very easy.

What's the difference between Redux and mvc and flux?

First of all, mvc,mvc divides the whole application into data layer, presentation layer and logic layer. When the data changes more, the system will become more complex, debugging will need more experience. Tell me again, flux. Flux is closer to Redux. Manage changes in data through event subscription. The callback loading mechanism is similar to that of Redux.

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