Understanding Facebook's React.js
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Slides on React.js covering the virtual DOM, JSX, components, component lifecycle, component state vs props
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Understanding Facebook's React.js
- 1. React A web tool developed and open-sourced by Facebook
- 2. • React is a javascript library, or tool • framework agnostic • lightweight and recursive What is React?
- 4. Benefits of React • Very modular .:. reusable • State-based .:. predictable • Independent .:. testable • High-performance, thanks to virtual DOM Listing Card Photo Gallery
- 5. React Virtual DOM the ability to re-render on every change!
- 6. • Manipulating the DOM is slow. • Javascript is fast. React Virtual DOM
- 7. Browser React Virtual DOM User’s View Real DOM Background Javascript Process Virtual DOM
- 8. Browser React Virtual DOM User’s View Real DOM null Background Javascript Process Virtual DOM <html> <button> Add text</button> <p></p> </html> First Render
- 9. Browser React Virtual DOM User’s View Real DOM <html> <button> Add text</button> <p></p> </html> Background Javascript Process Virtual DOM Real DOM populated, vDOM cleared
- 10. Browser React Virtual DOM User’s View Real DOM <html> <button> Add text</button> <p></p> </html> Background Javascript Process Virtual DOM <html> <button> Add text</button> <p>New text!</p> </html> User clicks ‘Add text’!
- 11. Browser React Virtual DOM User’s View Real DOM <html> <button> Add text</button> <p>New text!</p> </html> Background Javascript Process Virtual DOM <html> <button> Add text</button> <p>New text!</p> </html> User clicks ‘Add text’!
- 12. • What we get is a seamless, fluid ui • Only things that actually change, do change React Virtual DOM
- 13. • No need to implement the vDOM • But it’s important to know the foundation of the tools you choose! React Virtual DOM
- 14. JSX is a sugar-syntax for JS React JSX
- 16. React JSX JSX can be escaped from JSX-land to JS-land with {} JSX JS
- 17. React JSX That goes for comments too! JSX JS
- 18. React JSX It’s javascript! Use expressions. JSX JS
- 19. React JSX Hmm…. Why not just write javascript… ?
- 20. React JS
- 21. React JS
- 22. React JSX
- 23. component = view + controller React Components
- 24. • Forget MVC, think components. • Component = view/html + controller/js • JSX (sugar syntax that gets compiled to JS) React Components
- 25. React Components
- 26. AppTemplate UserDashboardPage Listing Card Photo Gallery Listing Card Photo Gallery Listing Card Photo Gallery Listing Card Photo Gallery Listing Card Photo Gallery Listing Card Photo Gallery HeaderNav React Components
- 27. • Based on state (props and state) • Uni-directional (re-renders every change*) • Composable (components in components) • Reusable (thanks to props) React Components
- 28. React Components
- 29. Component Lifecycle • componentWillMount() • componentDidMount() *client only • componentWillReceiveProps() • shouldComponentUpdate() • componentWillUpdate() • componentDidUpdate() • componentWillUnmount()
- 30. • React allows you to build react classes of components • From those classes, you build component instances, or elements • Factories create functions that return elements for a given class React.createClass() React.createElement() React.createFactory() React Components
- 31. Performance Components • High-performance, thanks to virtual DOM • Automatically applies best practices • UI handlers, batch manipulations
- 32. Summarizing Components • Very modular .:. reusable • State based .:. predictable • Independent .:. testable • High-performance, thanks to virtual DOM Listing Card Photo Gallery
- 33. in React Components State vs Props
- 34. React Components
- 35. Component Data • State — contained within a component; used to track changes within a component • Props — passed in from parent; think of these as arguments, or inputs to a component; do not change
- 36. Component State • Things that change within the component • Think of an input form, when the user types stuff —> Keep track of those changes in state • … or the currentPhotoIndex the user is on as he swipes through the PhotoGallery —> Keep track of those changes in state Photo Gallery 1 of 12
- 37. Component Props • Things that get passed into the component • Think of props as configurations to your component <PhotoGallery photoCount=“false” /> <PhotoGallery photoCount=“true” /> • The parent component passes down data into the child component via props. Photo Gallery 1 of 12 Photo Gallery