Top 10 React Developer Interview Questions

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Top 10 React Developer Interview Questions

Hen we need DOM measurements or to add methods to the components. ShouldComponentUpdate()– Returns true or false value based on certain conditions. If you want your component to update, return true else return false.

  • At the end of the day, hiring remains an art, a science — and a lot of work.
  • I myself have failed 100s of times before landing my first job.
  • This is a famous interview question with a lot of practical real world usage and implementations.
  • Also, you need to assure that it will not pollute the global window space.
  • Many developers also use it while practicing this technology.

It’s also a great way of learning about a candidate’s problem-solving skills. Ask how they managed conflict with their teammates and how they contributed to the resolution. A candidate’s answer to this question not only helps you assess how well they understand their job, it also tests their creativity and their ability to think on the fly.

It’s also the language programmers use to enable a site to load on a mobile device without losing its functionality. Our recruitment process ensures that our React developers and other specialists have the skills and experience to succeed as a part of your team. In a software development team, communicating well is very important. Many developers have a hard time speaking up to their leaders. Thus, speaking up and presenting an idea will show the candidate’s confidence, awareness, and persuasiveness. You should pay attention to how candidates explain Props and Context API. You can also ask them to write the code for these processes.

What’s the difference between an Element and a Component in React?

The Shadow DOM is a browser technology designed primarily for scoping variables and CSS in web components. The Virtual DOM is a concept implemented by libraries in JavaScript on top of browser APIs. Flow can’t guess the magic that framework does to make the string ref appear on this.refs, as well as its type . They force React to keep track of currently executing component. This is problematic because it makes react module stateful, and thus causes weird errors when react module is duplicated in the bundle.

front end developer react js interview questions

React uses this copy to determine what parts of the actual DOM need to change based on a user’s action. React then takes the change date from the Virtual DOM and selectively updates the actual DOM . Over time, this leads to significant performance improvements for the website or application.

The yield of the component is absolutely a function of the properties gave to it. Rendering the components is an important task in ReactJS. React router is used to decide which components are to be rendered and which ones should not. There is always a need to compile the files that contain JavaScript Code. This is usually done with the help of the JSX compiler which performs its task prior to the file entering the browser. It depends on a lot of factors such as the source or nature of the file or data.

What are the main features of React Intl?

A synthetic event is an object which acts as a cross-browser wrapper around the browser’s native event. It combines the behavior of different browser’s native event into one API, including stopPropagation() and preventDefault(). With JSX, a function is passed as the event handler instead of a string. Whenever any data changes in the React App, the entire UI is re-rendered in Virtual DOM representation.

State of a component can be updated using this.setState(). Once the calculations are done, the real DOM will be updated with only the things that have actually changed. Learn how to climb the corporate ladder if you’re a remote worker in tech, plus get 8 essentials to your continuous career growth.

front end developer react js interview questions

It is a predictable state container for JavaScript applications and is used for the entire application’s state management. Keys are used for identifying unique Virtual DOM Elements with their corresponding data driving the UI. They help React to optimize the rendering by recycling all the existing elements in the DOM. These keys must be a unique number or string, using which React just reorders the elements instead of re-rendering them.

How do you Create Nested Web Pages in HTML?

This occupation requires a good set of basic React js interview questions to assess the employee’s knowledge and skills. HR managers have a limited amount of time to evaluate the technical knowledge and practical experience of a candidate. Seeing how and when these hooks fire is vital to building stable components and will empower you to control the rendering procedure . Conditionally rendering a component is a common requirement in most applications. For example, a component might need to be rendered only if a certain set of data is available in your application’s state.

front end developer react js interview questions

Uses reusable/composable UI components to develop the view. You need to export the Store from the module where it created with createStore() method. Also, you need to assure that it will not pollute the global window space. Asynchronous code using setTimeout or requestAnimationFrame callbacks. The componentDidCatch logs the error information to an error tracking service. Hooks are the new feature introduced in React 16.8 version that facilitates us to use state and other React features without writing a class.

Props are one of the most basic ways of passing data between components in React. The candidate should be able to explain what props are and how they’re used to communicate between different components. Don’t forget to provide a couple of examples to demonstrate its usage in a real application. Function Componentsis the simplest way to create a component.


ComponentWillReceiveProps – Invoked when a component is receiving new props. Calling this.setState() within this function will not trigger an additional render. One common mistake is for code executed during this lifecycle method to assume that props have changed.

An interviewer might ask this question to understand the candidate’s familiarity with using conditionals in React and how they can be applied to class attributes. Arc is the radically different remote job search platform for developers where Front-end Developer React job companies apply to you. We’ll feature you to great global startups and tech companies hiring remotely so you can land a great remote job in 14 days. We make it easier than ever for software developers and engineers to find great remote jobs.

Like jQuery, this tool helps software developers work quickly. A great developer should be able to organize and prioritize their daily tasks to avoid being overwhelmed. Hence, they should know which tasks to do to keep the application development process chugging along. With that said, below are the top React Developer interview questions and what you should look for in their answers. ReactJS is a very powerful tool for front-end development. That’s why many companies are looking for React developers for their software development teams.

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Too many smaller components leading to over engineering or boilerplate. Integrating React into a traditional MVC framework requires some additional configuration. There is a learning curve for beginners who are new to web development. Easy to write unit and integration tests with tools such as Jest. Easy to integrate with frameworks since it is only a view library. Hooks let you use state and other React features without writing classes.

This allows a Provider component that supplies data to be defined, and allows nested components to consume context data via either a Consumer component or a useContext hook. 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. It is faster to shallow render a component than to fully render it. When a React project contains a large number of components, this performance difference can have a significant impact on the total time taken for unit tests to execute. All of these nested elements are nested under , thus HOC’s code will be able to access them as this.props.children. In addition, there are all sorts of build steps that can analyze your code and even optimize it for you.

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