React is a JavaScript library for building user interfaces that allows building large applications with data that changes over time. It uses a virtual DOM for efficiently updating the real DOM and a component-based approach where data flows from parent to child components. The core concepts of React include components, the virtual DOM, JSX, and data flow from parent to child and between sibling components using a unidirectional data flow model like Redux.

2. A JavaScript library for
building user interface
Facebook
2013年5月

3. Why React
We built React to solve one problem
building large applications with
data that changes over time

4. ReactDOM.render(
<h1>Hello, world!</h1>,
document.getElementById('root')
);

5. Declarative — 声明式编程
Component-Based
Learn Once, Write Anywhere

6. 核心
Component
Virtual DOM
JSX
Data Flow

7. Build Components

8. Division principle
☞ One thing
☞ DRY

10. JSX

11. VIRTUAL DOM
DOM?

12. DOM Diff

15. Data Flow

16. Component<->Component
父组件向子组件传值
子组件向父组件传值
兄弟组件之间传值

19. REDUX

21. setState() 异步
Reducer() return 一个新的对象
render() return 一个父节点

22. Thank you