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When to use class-based React components vs. function components?

In React, function components are now the go-to choice in most cases thanks to React Hooks (introduced in React 16.8). However, there are still situations where class components are needed.

Use Class Components When:

1: Working with Old Code:

If you're working on an old project that already uses class components, it’s usually best to stick with them instead of refactoring everything. Example:

class MyComponent extends React.Component {
  constructor(props) {
    super(props);
    this.state = { count: 0 };
  }
  render() {
    return <h1>{this.state.count}</h1>;
  }
}

2: Using Lifecycle Methods (before React 16.8):

Class components are needed for using lifecycle methods like componentDidMount, componentDidUpdate, etc., which were essential before Hooks. Example:

class MyComponent extends React.Component {
  componentDidMount() {
    console.log('Component has mounted!');
  }
  render() {
    return <h1>Hello</h1>;
  }
}

3: Creating Error Boundaries:

Only class components can be used to create error boundaries (used for handling JavaScript errors in child components). Example:

class ErrorBoundary extends React.Component {
  constructor(props) {
    super(props);
    this.state = { hasError: false };
  }
  static getDerivedStateFromError(error) {
    return { hasError: true };
  }
  render() {
    if (this.state.hasError) {
      return <h1>Something went wrong.</h1>;
    }
    return this.props.children;
  }
}

Use Function Components When:

1: Building New React Apps:

Function components are simpler and cleaner, making your code easier to write and maintain. Example:

function MyComponent() {
  const [count, setCount] = useState(0);
  return <h1>{count}</h1>;
}

Using Hooks for State & Side Effects:

useState and useEffect hooks replace the need for class component lifecycle methods. Example: jsx Copy Edit

function MyComponent() {
  const [count, setCount] = useState(0);
  
  useEffect(() => {
    document.title = `Count: ${count}`;
  }, [count]);
  
  return <h1 onClick={() => setCount(count + 1)}>{count}</h1>;
}

3: Better Performance & Smaller Code:

Function components have less overhead compared to class components (no need for this and constructor), making them faster and easier to optimize. Better Compatibility with Modern Features (e.g., React 18):

4: enter image description hereFunction components work better with React Suspense, Concurrent Mode, and other new features in React.

Comparison Table below Class Component VS Function Component

When to Use Each: For new React projects → Use function components with hooks. They're easier, cleaner, and the way React is heading. For legacy projects → Stick to class components, unless you want to refactor. For error boundaries → Class components are necessary. React has evolved, and function components are the future. They make it easier to manage state, side effects, and more, all with less boilerplate code

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