React is a JavaScript library developed by Facebook for building user interfaces using reusable components and a virtual DOM for efficient rendering.

What are React hooks?

Hooks are functions that allow you to use state and lifecycle features in functional components. Common hooks include useState, useEffect, useContext, and useReducer.

What is the virtual DOM?

The virtual DOM is an in-memory representation of the real DOM. React uses it to determine what changes need to be made and updates only those parts in the actual DOM efficiently.

React.js Interview Questions

81. What are server-side rendering and client-side rendering?

82. What are hydration mismatches in React?

83. How does hydration work internally?

84. What are the tradeoffs between CSR and SSR?

85. What is static site generation?

86. What are React developer tools used for?

87. How would you debug unnecessary renders in React DevTools?

88. What are common React anti-patterns?

89. How does React handle accessibility?

90. What accessibility mistakes are common in React applications?