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Subtitle:

Core principles governing the proper implementation of React Hooks

Core Idea:

React Hooks are JavaScript functions that follow specific rules governing where and how they can be called to ensure predictable component state management and lifecycle.

Key Principles:

1. Restricted Call Locations:
   • Hooks can only be called at the top level of React components or custom Hooks.
2. Consistent Ordering:
   • The order of Hook calls must remain consistent between renders to maintain state association.
3. Naming Convention:
   • Functions that implement Hook logic should be named with the "use" prefix (e.g., useState, useEffect).

Why It Matters:

• Predictable State Management:
  • Following Hook rules ensures React can correctly preserve state between re-renders.
• Component Debugging:
  • Consistent Hook placement makes component logic easier to follow and debug.
• Prevents Subtle Bugs:
  • Violating Hook rules leads to unpredictable behavior that can be difficult to diagnose.

How to Implement:

1. Follow the Two Core Rules:
   • Only call Hooks at the top level of functions
   • Only call Hooks from React function components or custom Hooks
2. Use ESLint Plugin:
   • Implement the eslint-plugin-react-hooks to automatically catch rule violations
3. Extract Custom Hooks:
   • Move complex Hook logic into separate custom Hooks to maintain readability

Example:

• Scenario:
  • Creating a component that displays window width but only on desktop devices
• Application:

// ✅ Correct implementation
function WindowSizeDisplay() {
  // Hooks called at top level
  const [width, setWidth] = useState(window.innerWidth);
  const isMobile = width < 768;
  
  useEffect(() => {
    const handleResize = () => setWidth(window.innerWidth);
    window.addEventListener('resize', handleResize);
    return () => window.removeEventListener('resize', handleResize);
  }, []);
  
  // Conditional rendering is fine
  if (isMobile) {
    return null;
  }
  
  return <div>Window width: {width}px</div>;
}
    ```
    
- **Result**:
    - Component correctly manages window size state and conditionally renders based on that state

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### **Connections**:

- **Related Concepts**:
	- React
	- 
    - Only call Hooks at the top level: Specific rule about Hook placement
    - Only call Hooks from React functions: Specific rule about Hook context
- **Broader Concepts**:
    - React Component Patterns: Organizational principles for React components
    - State Management: Strategies for managing application state

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### **References**:

1. **Primary Source**:
    - React Official Documentation - Rules of Hooks
2. **Additional Resources**:
    - ESLint Plugin for React Hooks: eslint-plugin-react-hooks

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### **Tags**:

#react #hooks #javascript #frontend #best-practices #component-design

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**Connections:**
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**Sources:**
- From: Rules of Hooks – React