Introduction to React js React js is a popular JavaScript library for building user interfaces. It was developed by Facebook and released in 2013. React allows developers to create reusable UI components.
Virtual DOM in React React uses a virtual DOM to improve performance. When a component's state changes, React updates the virtual DOM first. React then compares the virtual DOM with the real DOM and only updates the necessary elements.
JSX in React JSX is a syntax extension for JavaScript that allows for easier HTML-like code in React components. JSX is not required to use React, but it is commonly used for its readability and conciseness. JSX code is transpiled into regular JavaScript by tools like Babel.
Components in React Components are the building blocks of React applications. They can be either functional components or class components. Components can have their own state, props, and lifecycle methods.
State and Props in React State is internal data that belongs to a specific component and can be changed over time. Props are external inputs to a component that cannot be changed by the component itself. State and props are used to manage data flow and communication between components.
React Hooks Hooks are functions that enable functional components to use state and other React features. useState hook allows functional components to have local state. useEffect hook is used for side effects in functional components.
Routing in React React Router is a popular library for handling routing in React applications. It allows for declarative routing using components like <Route> and <Link>. React Router enables single-page applications with multiple views.
Redux in React Redux is a state management library commonly used with React. It helps manage global state in complex applications. Redux uses a single source of truth and immutability for state management.
Testing in React React applications can be tested using tools like Jest and Enzyme. Jest is a testing framework developed by Facebook for testing JavaScript applications. Enzyme is a testing utility for React that makes it easy to assert, manipulate, and traverse React components.
Conclusion React js is a powerful library for building interactive user interfaces. It promotes component-based architecture and reusability of code. React's large ecosystem of libraries and tools makes it a popular choice for front-end development.