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36 React Interview Questions You Should Ask a Prospective Developer in 2023

It is a new kind of architecture used for client-side web applications. With the help of JSX, it is easy to define how the user interface should look. Additionally, with JSX, the file containing the Javascript code can be used to write the HTML structures as well. The type of a component is determined by the way the tags are named. Both capitalized and dot notations are treated as React component while lowercase are treated as DOM elements. They can be useful when you need direct access to the DOM element or an instance of a component.

front end developer react js interview questions

It may also manage data that is passed down to it as props from other components, and it may use lifecycle methods, such as componentDidMount, to fetch data or perform other side effects. What is the difference between a static component and a dynamic component in React? In React, a static component is a component that is defined with a fixed set of properties or attributes and does not change during its lifecycle. A static component is defined using a simple JavaScript function that returns a tree of elements that represent the component’s UI. Functional components are considered simpler, easier to understand and test, and have better performance than class components. Class components are useful when you need to use lifecycle methods or the local state.

Explain the role of Reducer.

In this article, we will go over some React basics and then look at some interview questions and their proper answers to help you succeed in any React interview you may have. In this example, when the button is clicked, the handleClick function is called and the component’s state is updated. This causes a re-render of the component, and the displayed count is updated accordingly. React provides a built-in hook called useMemo for implementing memoization. UseMemo takes a function and an array of dependencies as arguments and returns a memoized value.

front end developer react js interview questions

Here’s a list of the most popular React JS interview questions and answers for 2023. Christopher Moore is a React Native mobile and full-stack developer with over a decade of experience. Over the last eight years, he has been running a web firm to create unique applications and custom solutions for his clients. He specializes React Native, React (Web), Laravel, Node.js, and GraphQL development as well as developing his skills with Go.

Why should component names start with capital letters?

Idempotence is a concept used in mathematical logic and computer science. Simply saying, it means that the same operation should always return the same output if provided the same input. Its relation with the Functional Programming rests in the fact that the concept of idempotence reflects one of the core principles of FP, that is, Pure functions. On the other hand, as a recruiter, no matter which hiring strategy you decide to implement, it’s essential to have a good interview process in place.

front end developer react js interview questions

They are used to transfer data from one component to the next (parent component to child component). They are typically used to render dynamically generated data. Client-side rendering (CSR) is when the React application is rendered entirely in the browser, using JavaScript. The browser requests the JavaScript bundle from the server and then renders the components on the client side.

What are Custom Hooks?

The simplest approach is to simply pass a selectedUserAddress prop from each component to the next in the hierarchy from the source component to the deeply nested component. When developers first start using React after developing traditional web applications, they often use CSS classes for styling because they are already familiar with the approach. With keys, React would actually re-order the DOM elements, instead of rendering a lot of nested DOM changes. This can serve as a huge performance enhancement, especially if the DOM and VDOM/React Elements being used are costly to render. With the above list, we have tried to present some trending ReactJS interview questions that not only help scrutinize the right candidate but also help contenders crack the right interview.

These actions cannot be immediately processed by the Redux store, so they require additional logic to handle their completion. To use react-i18next in your React application, you would install it using npm and then configure it in your index.js file. After that, you can use the useTranslation Hook to access the translations in your components.

Differentiate between States and Props.

Forms allow the users to interact with the application as well as gather information from the users. Forms can perform many tasks such https://wizardsdev.com/en/vacancy/front-end-developer-react/ as user authentication, adding user, searching, filtering, etc. A form can contain text fields, buttons, checkbox, radio button, etc.

  • These components are considered “pure” because they are only concerned with the rendering of the data and do not have side effects.
  • It also allows server-side rendering, which is also helpful to boost the SEO of your app.
  • It is a React extension which allows writing JavaScript code that looks similar to HTML.
  • The parent component passes the state as props to the controlled component and also handles any changes to the state via callback functions.
  • JSX is a language that React uses to embed an HTML template in code.
  • Today, developers have to be tech-savvy and be able to create interactive web applications.

When a React component’s state changes, React updates the Virtual DOM, instead of directly updating the actual DOM. Custom Hooks can receive arguments and return values, just like a regular function, but they also have the ability to manage state and perform side-effects. By abstracting state and behavior into a Custom Hook, you can improve the readability and maintainability of your code. Optimize the loading time of your application by using techniques like code minification, compression, and caching.

ReactJS Interview Questions on Components

Developer primarily use React to create Single Page Applications and the library focuses solely on the view layer of MVC. Implementing internationalization in a React application can greatly improve the user experience for users who speak different languages and are located in different regions. It’s an important consideration for any application that aims to have a global reach. In summary, the Virtual DOM in React acts as an optimization to increase the speed and efficiency of updates to the user interface. Examples of HOCs include the withRouter HOC from react-router and the connect HOC from react-redux. In summary, actions describe what should change, while reducers define how the state should change in response to the actions.

front end developer react js interview questions

The DOM represents an HTML document with a logical tree structure. Each branch of the tree ends in a node, and each node contains objects. React hooks were added in v16.8 to allow us to use state and other React features without having to write a class. One difference we must consider is the naming of our events, which are named in camelCase rather than lowercase.

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