Legacy vs Current React
Legacy React vs Current React: A Comparison
React has evolved significantly since its earlier days. Below is a table highlighting the key differences between Legacy React (before Hooks) and Current React (React 16.8+ and beyond):
Feature / Aspect | Legacy React (Pre React 16.8) | Current React (React 16.8 and above) |
---|---|---|
Component Types | Class components only for state & lifecycle | Functional components with Hooks |
State Management | this.state , this.setState() |
useState , useReducer |
Lifecycle Methods | componentDidMount , componentDidUpdate , etc. |
useEffect replaces many lifecycle methods |
Hooks | Not available | Introduced in React 16.8 (useState , useEffect , etc.) |
Rendering | Manual control via lifecycle methods | More declarative with hooks |
Context API | Verbose and harder to use | Simplified and hook-compatible (useContext ) |
Refs | React.createRef() used only in class components |
useRef available in functional components |
Code Splitting | Manual setup required | Built-in support with React.lazy , Suspense |
Concurrent Features | Not supported | Supported in modern React (Concurrent Mode, startTransition ) |
JSX Transform | Requires React in scope |
New JSX transform (React 17+) removes this need |
Strict Mode Enhancements | Limited | Better dev-time checks with React.StrictMode |
Testing & Tooling | Basic tooling support | Advanced dev tools, testing libraries optimized for hooks |
Performance Optimizations | Manual shouldComponentUpdate , PureComponent |
React.memo , useMemo , useCallback for fine control |
Server Components (Emerging) | Not available | Supported (experimental/gradual adoption) |
As you can see, the evolution of React has greatly simplified development while increasing flexibility and performance. Embracing modern React practices helps build more maintainable and efficient applications.
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