ReactJs interview questions

Master ReactJs interview questions with 40+ curated problems, answer outlines, and placement-focused preparation.

Preview Questions

  1. What is React?

    React is an open-source JavaScript library developed by Facebook for building user interfaces. It enables developers to create interactive and dynamic web applications using reusable components. React follows a...

  2. Explain what is JSX in React js?

    JSX stands for JavaScript XML and enables writing HTML-like syntax directly within JavaScript code. It allows developers to write component structures using familiar HTML tags inside JavaScript. JSX code is not valid...

  3. What is a component in React?

    A component in React is a reusable piece of UI that combines structure, styling, and behavior. Components enable breaking complex UIs into smaller, manageable pieces. React supports two types of components: functional...

  4. Explain Virtual DOM in ReactJs?

    The Virtual DOM is an in-memory representation of the actual DOM maintained by React. It's a lightweight JavaScript object that mirrors the structure of the real DOM. When component state changes, React creates a new...

  5. What are Props in React?

    Props stand for properties and are the mechanism for passing data from parent components to child components. Props are read-only and immutable preventing child components from modifying parent data. Props are passed as...

  6. What is State in React?

    State represents the internal data of a component that can change over time. Unlike props which are immutable, state can be modified enabling dynamic component behavior. In functional components, state is managed using...

  7. Explain the difference between Props and State.

    Props are passed from parent to child components while state is internal to a component. Props flow downward in the component hierarchy while state is isolated within components. Props are immutable and cannot be...

  8. What are Hooks in React?

    Hooks are functions enabling functional components to use state and other React features. Before hooks, only class components could use state making code organization difficult. The useState hook enables adding state to...