How to Enable Fast Refresh in Nextjs

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Introduction

Enhancing the developer experience is crucial in today’s fast-paced software development environment. Fast Refresh in NextJS significantly improves development workflow by providing instant feedback on code changes without losing component state. This feature is particularly beneficial for developers working with the React framework as it boosts productivity and efficiency. This detailed guide will explore how to enable and optimize Fast Refresh in NextJS, complete with practical examples to help you seamlessly integrate this feature into your Next.js projects.

Also, Read: Complete Next.js Tutorial: Mastering Full Stack Development

What is Fast Refresh in NextJS?

Fast Refresh in NextJS combines the best aspects of full page reloads and hot module replacement (HMR) technologies, offering a seamless way to update your application’s UI without losing state. It is automatically enabled in development mode, allowing developers to see changes in real-time.

Step-by-Step Guide to Enable Fast Refresh in NextJS

Step 1: Setting Up Your Next.js Project

First, ensure you have Node.js installed on your computer. Then, set up a new Next.js project by running the following commands:

Begin by creating a new Next.js project if you haven’t already:

npx create-next-app my-next-app
cd my-next-app

This sets up a new project, primed with Fast Refresh enabled by default, provided it runs in development mode (next dev).

Step 2: Verify Default Settings

Fast Refresh is enabled by default under the following conditions:

  • The project is in development mode.
  • There are no custom Babel or Webpack configurations that disable HMR.

Ensure your next.config.js and .babelrc files do not contain settings that might conflict with these defaults.

Also, Read: Next.js Dynamic Route Segments: A step by step with Examples

Step 3: Customize Fast Refresh

You might want to customize the behavior of Fast Refresh in Next.js to better fit your project’s needs. Adjustments can be made in the next.config.js file:

// next.config.js
module.exports = {
  reactStrictMode: true,
  onDemandEntries: {
    maxInactiveAge: 25 * 1000, // Amount of time (in ms) a page can stay in memory without being accessed
    pagesBufferLength: 2,      // Number of pages that should stay in memory
  },
}

These settings help manage how pages are cached during development, affecting Fast Refresh efficiency.

Step 4: Implementing Fast Refresh with React Hooks

Using React Hooks with Fast Refresh in Next.js can enhance your development experience by maintaining state between updates. Here’s an example using useState and useEffect:

import React, { useState, useEffect } from 'react';

function Timer() {
    const [seconds, setSeconds] = useState(0);

    useEffect(() => {
        const interval = setInterval(() => {
            setSeconds(seconds => seconds + 1);
        }, 1000);
        return () => clearInterval(interval);
    }, []);

    return (
        <div>
            <h1>Elapsed Time: {seconds} seconds</h1>
        </div>
    );
}

export default Timer;

In this example, the timer state is preserved during development updates, demonstrating how Fast Refresh seamlessly integrates with function components and hooks.

Additional Examples of Fast Refresh in Next.js

Example: Dynamic Style Updates

Fast Refresh also enhances the experience of styling React components. Here’s a simple example of updating styles dynamically:

Also, Read: What is SSR in NextJS? Benefits, Implementation and Examples

import React, { useState } from 'react';

function DynamicStyling() {
    const [color, setColor] = useState('blue');

    return (
        <div style={{ color }}>
            <h1>Welcome to Next.js!</h1>
            <button onClick={() => setColor('red')}>Change Color</button>
        </div>
    );
}

export default DynamicStyling;

Changes to the color state or button functionality will be reflected instantly, thanks to Fast Refresh.

Example: Incremental Development of New Features

When developing new features, such as adding a new button or implementing a new API call, Fast Refresh ensures that the rest of your application remains functional as you integrate and test new code. Here’s an example:

import React from 'react';
import axios from 'axios';

class FetchData extends React.Component {
    state = { data: null };

    componentDidMount() {
        axios.get('/api/data').then(response => this.setState({ data: response.data }));
    }

    render() {
        return (
            <div>
                <h1>Data Fetched from Server:</h1>
                <pre>{JSON.stringify(this.state.data, null, 2)}</pre>
            </div>
        );
    }
}

export default FetchData;

This example fetches data from an API and displays it. With Fast Refresh, you can modify the API endpoint or adjust the display without re-fetching the data or restarting the server.

Also, Read: Exploring Next.js Data Fetching Methods: A step by step example

Conclusion

Fast Refresh in NextJS is a transformative feature for developers using Next.js and React. It not only saves time but also enhances the development experience by allowing instant feedback and maintaining state during the development. By following this guide, integrating examples, and adhering to best practices, developers can fully leverage Fast Refresh to optimize productivity and streamline their development processes. As you continue to develop with Next.js, remember that Fast Refresh is a powerful tool that can significantly improve your development workflow.

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