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:
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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
