TCS Interview Questions and Answers

To avoid re-rendering, use shouldComponentUpdate or React.memo

• Use shouldComponentUpdate to compare current and next props/state

• Use React.memo to memoize functional components

• Use useMemo to memoize expensive computations

• Use useCallback to memoize event handlers

• Use PureComponent for class components

Refs are a way to access DOM nodes or React components directly. They can be used to get input values.

• Refs provide a way to access DOM nodes or React components directly.

• They are commonly used to get input values or trigger imperative animations.

• Refs can be created using the `createRef()` method or by using a callback function.

• To get the value of an input using refs, you can assign a ref to the input element and access its value property.

Error handling in React can be done using try-catch blocks, error boundaries, and handling asynchronous errors.

• Use try-catch blocks to handle synchronous errors

• Use error boundaries to catch errors in child components

• Handle asynchronous errors using promises or async/await

• Use third-party libraries like Sentry or Bugsnag for better error tracking

• Display user-friendly error messages to improve user experience

Lazy Loading and Suspense are techniques used to improve performance by loading components and data only when needed.

• Lazy Loading delays the loading of non-critical resources until they are needed, reducing initial load time.

• Suspense allows components to wait for data to load before rendering, improving user experience.

• Lazy Loading and Suspense can be used together to optimize performance and user experience.

• Example: A website with a large image gallery can use Lazy Loading t...read more

componentWillUnmount is a lifecycle method in React that is called right before a component is unmounted and destroyed.

• componentWillUnmount is used to perform any necessary cleanup tasks before a component is removed from the DOM.

• It is commonly used to cancel any pending network requests, remove event listeners, or clear timers or intervals.

• The method is called automatically by React when a component is about to be unmounted.

• It is important to clean up any resources or subscr...read more