How to Build a Progressive Web App With Svelte and Service Workers

Progressive Web Apps (PWAs) combine the best web and mobile apps to offer a superior user experience. Building a PWA with Svelte and Service Workers can elevate your web applications to the next level. Here’s a comprehensive guide on how to create a PWA using these powerful tools.

What You Need to Know Before You Start

Before delving into the building process, it's essential to understand the key components:

Svelte: A modern JavaScript framework that compiles components into highly optimized vanilla JavaScript.
Service Workers: Background scripts that enable features like offline capability and push notifications for your web app.

Setting Up Your Svelte Project

To get started, ensure you have Node.js installed on your machine. Follow these steps:

Open your terminal and create a new Svelte project:

npx degit sveltejs/template my-svelte-app

Navigate into your project folder:

cd my-svelte-app

Install the necessary dependencies:

npm install

Adding Service Workers

Service Workers are crucial for making your web app progressive. Here's how to set them up:

Create a new directory in the `src` folder named `service-worker` and a file inside named `service-worker.js`.
In the `service-worker.js` file, you can add the following basic code to cache your assets:


self.addEventListener('install', (event) => {
    event.waitUntil(
        caches.open('my-cache').then((cache) => {
            return cache.addAll([
                '/',
                '/global.css',
                '/build/bundle.css',
                '/build/bundle.js',
            ]);
        })
    );
});
self.addEventListener('fetch', (event) => {
    event.respondWith(
        caches.match(event.request).then((response) => {
            return response || fetch(event.request);
        })
    );
});

Next, you need to register the service worker in your Svelte application's entry point. Open the `src/main.js` file and add the following code:


if ('serviceWorker' in navigator) {
    navigator.serviceWorker.register('/service-worker.js')
    .then(() => console.log('Service Worker registered'))
    .catch((error) => console.error('Service Worker registration failed:', error));
}

Creating the Manifest File

A web app manifest is essential for defining how your app appears when installed on a user's device. Create a `manifest.json` file in the public directory with the following content:


{
    "name": "My Svelte App",
    "short_name": "SvelteApp",
    "start_url": "/",
    "display": "standalone",
    "background_color": "#ffffff",
    "theme_color": "#ffffff",
    "icons": [
        {
            "src": "icon-192x192.png",
            "sizes": "192x192",
            "type": "image/png"
        },
        {
            "src": "icon-512x512.png",
            "sizes": "512x512",
            "type": "image/png"
        }
    ]
}

Make sure to link this manifest file in your `index.html` within the `` section:

<link rel="manifest" href="/manifest.json">

Testing Your PWA

To test your PWA, start your development server using:

npm run dev

Open your browser and navigate to `http://localhost:5000`. Use Chrome DevTools to inspect your application. Go to the "Application" tab to check if the service worker is registered and the manifest is properly configured.

Conclusion

By following these steps, you can effectively build a PWA using Svelte and Service Workers, enhancing user experience through offline capabilities and a mobile-friendly interface. As you expand your app, consider implementing more advanced features such as push notifications and background sync.

How to Build a Progressive Web App With Svelte and Service Workers