Essel Group Interview Questions and Answers

React lifecycle methods are functions that are called at different stages of a component's life.

• Mounting: constructor(), render(), componentDidMount()

• Updating: render(), componentDidUpdate()

• Unmounting: componentWillUnmount()

• Error Handling: componentDidCatch()

Debounce the API call on input change to optimize performance.

• Implement a debounce function to delay the API call until the user has finished typing.

• Set a time interval for the debounce function to wait before making the API call.

• Cancel the previous API call if a new input change occurs before the time interval is up.

• Use a loading spinner to indicate to the user that the API call is in progress.

• Consider using a caching...read more

useMemo is a hook in React that memoizes the result of a function and returns the cached value when the inputs don't change.

• useMemo is used to optimize performance by avoiding unnecessary re-renders.

• It takes two arguments: a function that returns a value and an array of dependencies.

• If any of the dependencies change, the function is re-executed and the new value is cached.

• Example: useMemo(() => expensiveFunction(a, b),...read more

JWT token is a JSON Web Token used for authentication and authorization. OAuth2 is an authorization framework.

• JWT token is a compact and self-contained way to transmit information between parties as a JSON object.

• OAuth2 is an authorization framework that enables a third-party application to obtain limited access to an HTTP service.

• JWT token is used for authentication and authorization, while OAuth2 is used for authoriz...read more