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React Introduction

React is an open source JavaScript library first released by Facebook in 2013 to help developers build user interfaces, especially single-page applications (SPAs). The core idea of ​​React is to build reusable UI components in a componentized way, allowing developers to manage the state and views of the application more efficiently.

1. Componentization​

In React, the user interface is split into multiple independent, reusable components. Each component is a JavaScript function or class that returns a React element (usually an HTML tag). This componentized design allows developers to reuse the same components in different places, thereby improving development efficiency and code maintainability.

2. Virtual DOM​

React introduces the concept of virtual DOM to improve the performance of updating the user interface. When the state or properties of a component change, React does not update the real DOM immediately, but first creates a virtual DOM tree, calculates the changes, and then updates the smallest changes to the real DOM. This approach greatly reduces the overhead of directly manipulating the DOM and improves the performance of the application.

3. One-way data flow​

React uses one-way data binding, that is, the flow of data between components is one-way, the parent component passes data to the child component, and the child component sends data by calling the callback function of the parent component. This design pattern makes the data flow more controllable and easy to debug and maintain.

4. JSX syntax​

React uses JSX (JavaScript XML) syntax, which is a syntax extension of JavaScript that allows developers to write HTML tags directly in JavaScript code. Although JSX is not required, it makes the structure of components more intuitive and enhances readability. JSX will be converted to standard JavaScript code during the build process.

5. Lifecycle methods​

Each React component has a series of lifecycle methods to control the creation, update, and uninstallation of components. These methods allow developers to insert custom code logic at specific times, such as obtaining data when the component is loaded and handling side effects when the component is updated. Common lifecycle methods include componentDidMount, componentDidUpdate, and componentWillUnmount.

6. Hooks​

React introduced Hooks in version 16.8, which is a feature that allows function components to have state and lifecycle characteristics. The most commonly used Hooks include useState and useEffect. The introduction of Hooks makes function components more flexible and powerful. Developers no longer need class components to use function components to implement complex logic.

7. State Management​

In React applications, state is one of the core concepts of components. State represents the data of a component at a specific point in time, and React will re-render the component based on changes in state. In addition to the local state of components, React also supports global state management. Common libraries include Redux and MobX, which can help manage the state in complex applications and improve the maintainability of applications.

8. Ecosystem​

React has a rich ecosystem, providing a large number of tools and libraries to extend its functionality. Common tools include:

  • React Router: used to manage routes in applications and support page navigation in single-page applications.

  • Redux: used for global state management, suitable for large applications.

  • Axios: used to handle HTTP requests and data acquisition.

9. Community and Support​

React has an active community, and developers can get support and resources through forums, GitHub, Stack Overflow and other platforms. In addition, the continued support of Facebook and other large companies has kept React strong and stable in the technology stack.

10. Summary​

React's design philosophy and features make it a powerful tool for building modern web applications. Its components, virtual DOM, one-way data flow and other features enable developers to build efficient, flexible and maintainable user interfaces. Over time, the React ecosystem continues to expand, and more and more developers and companies choose to use React to build their applications. Whether you are a beginner or an experienced developer, mastering React is a valuable skill.

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