ReactJS Interview Question: Functional Components vs Class Components

One frequently asked ReactJS interview question is "What are the differences between functional components and class components in React, and when would you choose to use one over the other?"

Functional components and class components are the two primary ways to create components in React.

Functional Components:

• They are simpler and more lightweight.
• They are just plain JavaScript functions that take props as arguments and return React elements.
• They do not have access to state or lifecycle methods.
• They are easier to test and may have better performance.

Class Components:

• They are more feature-rich and have access to state and lifecycle methods.
• They are defined using ES6 classes and must extend from React.Component.
• They are useful for complex components that require state management and lifecycle methods like componentDidMount.
• They might be harder to read and test compared to functional components.

When to choose one over the other:

• Use functional components for simple presentational components that do not need state or lifecycle methods.
• Use class components for complex stateful components that require lifecycle methods and state management.