Uplers Reactjs Developer Interview Questions and Answers

An anti-pattern in React is a common mistake or bad practice that should be avoided.

• Using index as key in lists can cause issues with component re-rendering

• Using setState in a loop can lead to unexpected behavior

• Not using PureComponent or memoization for performance optimization

• Overusing context instead of props drilling can make code harder to maintain

Flux is a design pattern for managing data flow in React applications, while Grid is a layout system for organizing content.

• Flux is useful for managing complex data flow in large applications, ensuring data consistency and predictability.

• Grid is useful for creating responsive layouts and organizing content in a visually appealing way.

• Flux helps in maintaining a unidirectional data flow, making it easier to debug and un...read more

Optimizing a React application involves code splitting, lazy loading, using memoization, minimizing re-renders, and optimizing network requests.

• Implement code splitting to load only necessary code for each route or component.

• Use lazy loading to load components only when they are needed.

• Memoize expensive calculations or functions using useMemo or useCallback.

• Minimize re-renders by using shouldComponentUpdate or React.me...read more

Higher order components are functions that take a component and return a new component with additional functionality.

• Higher order components are used for code reuse and logic sharing.

• They allow you to abstract common logic into a reusable component.

• Examples include components that handle authentication, data fetching, or styling.

State is mutable and controlled by the component itself, while props are immutable and passed down from parent components.

• State is managed within a component and can be changed using setState() method

• Props are passed down from parent components to child components

• State can be updated and re-render the component, while props are read-only

Using callback functions or props to pass data from child to parent in React

• Use callback functions to pass data from child to parent

• Pass data as props from child component to parent component

• Utilize state management libraries like Redux to pass data between components

Optimizing performance of React application involves code splitting, lazy loading, minimizing bundle size, using memoization, and optimizing render methods.

• Implement code splitting to load only necessary code for each route or component.

• Utilize lazy loading to load components only when they are needed.

• Minimize bundle size by removing unnecessary dependencies and using tools like Webpack Bundle Analyzer.

• Use memoization ...read more

Context API is a feature in React that allows sharing data between components without having to pass props through every level of the component tree.

• Context API provides a way to pass data through the component tree without having to pass props down manually at every level.

• It is useful for passing global data like themes, user authentication, etc. to multiple components.

• Context API consists of three main parts: Provide...read more

Props drilling is the process of passing props from a parent component to multiple levels of nested child components.

• Props drilling can lead to a lot of unnecessary passing of props through intermediate components.

• It can make the code harder to maintain and understand.

• One way to avoid props drilling is by using React Context API or Redux for managing global state.

Redux is a predictable state container for JavaScript apps.

• Redux is a state management library for JavaScript applications.

• It helps in managing the state of the application in a predictable way.

• Redux follows a unidirectional data flow pattern.

• Actions are dispatched to update the state in the store.

• Components can subscribe to the store to get updates.

Redux is implemented in React by creating a store, defining actions, creating reducers, and connecting components.

• Create a Redux store using createStore() function from 'redux' package

• Define actions as plain objects with a 'type' property

• Create reducers to specify how the state changes in response to actions

• Connect components to the Redux store using connect() function from 'react-redux' package