A service worker is a script that your browser runs in the background, separate from a web page, opening the door to features that don't need a web page or user interaction. One of its key uses is to cache static assets, allowing your website to function offline or in poor network conditions.

Here's a step-by-step guide to creating an offline page:

1. Register a Service Worker:

  • Create a Service Worker File:
    • Create a new JavaScript file, e.g., sw.js, and place it in your project's root directory.
  • Register the Service Worker:
    • Add the following JavaScript code to your main HTML file, typically in the <head> section:
    if ('serviceWorker' in navigator) {
    window.addEventListener('load', () => {
        navigator.serviceWorker.register('sw.js')
            .then(registration => {
                console.log('Service Worker registered:', registration);
            })
            .catch(error => {
                console.error('Service Worker registration failed:', error);
            });
    });
}

2. Cache Static Assets:

  • Update sw.js:
    • Inside sw.js, use the cache API to store static assets:
    self.addEventListener('install', event => {
    event.waitUntil(
        caches.open('my-cache-name')
            .then(cache => {
                return cache.addAll([
                    '/',
                    '/index.html',
                    '/style.css',
                    '/script.js',
                    // Add more files as needed
                ]);
            })
    );
});

self.addEventListener('fetch', event => {
    event.respondWith(
        caches.match(event.request)
            .then(response => {
                return response || fetch(event.request);
            })
    );
});

3. Create a Manifest File:

  • Create a Manifest File:
    • Create a new file named manifest.json in your project's root directory.
  • Configure the Manifest File:
    • Add the following JSON content to the manifest file:
    {
    "name": "My Offline App",
    "short_name": "My App",
    "description": "This app works offline!",
    "start_url": "/",
    "display": "standalone",
    "background_color": "#ffffff",
    "theme_color": "#3367D6",
    "icons": [
        {
            "src": "/icon-192x192.png",
            "sizes": "192x192",
            "type": "image/png"
        },
        // Add more icons as needed
    ]
}

4. Add the Manifest Link:

  • Link to the Manifest:
    • Add a <link> tag to your HTML file's <head> section:
    <link rel="manifest" href="manifest.json">

How It Works:

  1. Service Worker Registration: The browser registers the service worker, allowing it to intercept network requests.
  2. Caching Static Assets: The service worker caches static assets like HTML, CSS, and JavaScript files.
  3. Offline Access: When the user is offline, the browser serves the cached assets, allowing the website to function as expected.
  4. Manifest File: The manifest file provides metadata about your app, including icons and theme colors, enabling it to be installed as a standalone app on mobile devices.

By following these steps, you can create a robust offline experience for your users, ensuring that your website remains accessible even when they're not connected to the internet.



Péntek, november 15, 2024

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