Top 10 tricks to make your React App Faster

React is one of the most popular, efficient, and powerful open-source JavaScript libraries for building dynamic and interactive user interfaces. It has the capability to build a large-scale application. But when the app grows it becomes very important to optimize the codebase so that it can work fast and smoothly and can handle many requests at a time without performance delay.

Top 10 tricks to make your React App Faster:

1. Use React.memo() and React.useMemo():

You can use React.memo() and React.useMemo() because they are two higher-order components that can help you memorize your components and prevent unnecessary re-renders. React.memo() is used to memoize the entire component and React.useMemo() memoizes the specific value or function within the component. Let's discuss in detail:

React.memo():

Imagine you have a complex component that takes time to render. If the props of the component haven't changed, you don't want it to re-render unnecessarily. That's where React.memo() comes in. It wraps your component and remembers its last rendered output based on its props.

Here is the sample code of React.memo():

const ExpensiveComponent = React.memo(props => {
    // This component might do heavy calculations or render complex visuals
    return <div>{/* ... */}</div>;
});

function MyComponent() {
    // Only re-renders ExpensiveComponent if its props change
    return <ExpensiveComponent text="Hello world!" />;
}

React.useMemo():

This helps with expensive calculations or functions within a component. Instead of recalculating them on every render, React.useMemo() stores the result and only re-computes it if the dependencies (the values used for the calculation) change.

Here is the sample code of React.useMemo():

const MyComponent = () => {
    const memoizedValue = useMemo(() => {
        return expensiveFunction(props.data); // Only calculated when props.data changes
    }, [props.data]); // Recalculate if 'props.data' changes

    return <div>{memoizedValue}</div>;
};

2. Use Lazy Loading:

You can use the Lazy loading technique to significantly improve the performance of your react app by reducing the initial load time. This technique delays the loading of components unit they are actually needed and will optimize the initial page load time.

import React, { Suspense } from 'react';
const OtherComponent = lazy(() => import('./OtherComponent'));

function MyComponent() {
    return (
        <React.Suspense fallback={<div>Loading...</div>}>
            <OtherComponent /> // Only loaded when user scrolls down
        </React.Suspense>
    );
}

3. Use Pure Components:

These are special components that implement the `PureComponent` class and override the `shouldComponentUpdate` lifecycle method. This method checks if the props and state have changed before allowing the component to re-render. If the props and state have not changed then the render part is skipped. This means that they can only re-render when their props and state change.

class MyPureComponent extends PureComponent {
    render() {
        return <div>{this.props.name}</div>;
    }
}

4. Immutable Data Structures:

Instead of directly modifying the data objects, use immutable data structures like Map from Immutable.js. These Libraries create new versions of the data whenever you want to change it, keeping the original data untouched. This helps React efficiently detect the changes and only update the necessary parts to avoid unnecessary re-renders.

const state = Map({ items: [] });

// Update state immutably
const updatedState = state.set('items', [...state.get('items'), newItem]);

5. Image Optimization:

Images can significantly impact website loading times. Optimize them by:

• Reducing file size by compression: Use tools like Imagemin or webpack plugins to compress images without sacrificing quality.
• Choosing the right format: Use JPEG for photos, PNG for graphics with transparency, and WebP for a modern format with better compression.
• Lazy loading images: Only load images when they appear in the viewport, using libraries like react-lazy-load-image.

6. Use of Multiple Chunk Files:

If your react app is complex and has too many files then instead of loading all your code in one bundle, you can divide it into smaller chunks based on features, routes, or other logical grouping. These chunks are then loaded dynamically as the user interacts with your react app.

7. CDN:

You can serve your static assets like images, scripts, and styles from a CDN geographically closer to your users. By applying this technique you can reduce the latency and improve the loading time, especially for users far from your server. You can use any CDN of your choice.

8. Server Side Rendering:

Server Side Rendering can be very beneficial to speed up the application loading time. Instead of sending JavaScript bundles and letting the browser render everything, the SSR pre-renders your react app on the server and sends the HTML to client side. SSR pre-renders your React app on the server, providing faster initial load times and improved SEO.

9. Performance Testing Tool:

The performance Testing Tool can help you to identify the bottlenecks in your react ap p and make improvements. Here are some performance Testing Tool you can use:

• React DevTool Profiler: Use this tool to analyze the components rendering time and identify the inefficient components.
• Lighthouse: You can audit your website and based on the recommendations you can improve the performance, SEO, and accessibility.
• WebPageTest: If you have deployed your react app you can run performance tests from different locations and it will provide you the detailed reports.

10. Use Production Mode Flag in Webpack:

By using this trick you can automatically optimize your react app, if you are using the `webpack 4` as a module bundler then you can make some changes by setting the mode option to production. This will simply command the webpack to use built-in optimization in the react app.

module.exports = {
mode: 'production'
};

Conclusion:

In Conclusion, Remember, the best approach to make the react app faster is a combination of different techniques tailored to your specific application and user base. These are just a few tips to help you make your React apps faster. There are many other techniques that you can use, so be sure to experiment and find what works best for your app.