React - React Fiber

Introduction to React Fiber architecture

React Fiber is the new reconciliation engine in React 16 and above. It is a complete rewrite of the older reconciliation algorithm, designed to enable incremental rendering, improve responsiveness, and make it easier to handle complex updates. This tutorial provides an introduction to React Fiber architecture, its key concepts, and its benefits.

What is React Fiber?

React Fiber is a reimplementation of the React core algorithm. It introduces a new concept called "fibers" which are units of work that can be paused, resumed, and reused. The Fiber architecture is designed to improve the efficiency and performance of the React rendering process.

// Simplified representation of a fiber
const fiber = {
    type: 'div',
    props: { children: 'Hello, world!' },
    stateNode: document.createElement('div'),
    return: null,
    child: null,
    sibling: null,
    effectTag: null,
    alternate: null,
};
                

Incremental Rendering

Incremental rendering allows React to break rendering work into chunks and spread it out over multiple frames. This makes it possible to pause rendering work to handle high-priority updates, improving the responsiveness of the application.

// Example of incremental rendering
class App extends React.Component {
    state = { items: Array.from({ length: 10000 }, (_, i) => i) };

    render() {
        return (
            <div>
                {this.state.items.map(item => <div key={item}>Item {item}</div>)}
            </div>
        );
    }
}
                

Improved Responsiveness

React Fiber improves responsiveness by allowing rendering work to be paused and resumed as needed. This enables React to handle high-priority updates, such as user interactions and animations, without blocking the main thread.

// Example of handling high-priority updates
class App extends React.Component {
    state = { count: 0 };

    componentDidMount() {
        setInterval(() => {
            this.setState(state => ({ count: state.count + 1 }));
        }, 1000);
    }

    render() {
        return (
            <div>
                <h1>Count: {this.state.count}</h1>
                <input type="text" placeholder="Type something..." />
            </div>
        );
    }
}
                

Handling Complex Updates

Fiber makes it easier to handle complex updates, such as animations and gestures. By breaking rendering work into smaller units, React can manage these updates more efficiently.

// Example of handling complex updates
class Animation extends React.Component {
    state = { position: 0 };

    componentDidMount() {
        this.interval = setInterval(() => {
            this.setState(state => ({ position: state.position + 1 }));
        }, 16);
    }

    componentWillUnmount() {
        clearInterval(this.interval);
    }

    render() {
        return (
            <div style={{ position: 'absolute', left: `${this.state.position}px` }}>
                I'm moving!
            </div>
        );
    }
}
                

Best Practices

Here are some best practices for optimizing your React applications with Fiber:

• Use shouldComponentUpdate, React.memo, or useMemo to prevent unnecessary re-renders.
• Keep components small and focused to minimize the impact of updates.
• Leverage concurrent mode features for better performance and responsiveness.
• Use requestIdleCallback or similar techniques for non-urgent updates.

Summary

In this tutorial, you learned about React Fiber, the new reconciliation engine in React 16 and above. Fiber enables incremental rendering, improves responsiveness, and makes it easier to handle complex updates. By understanding and leveraging Fiber's capabilities, you can optimize the performance and efficiency of your React applications.