Advanced Offline Caching Techniques

1. Introduction

In this lesson, we will explore advanced offline caching techniques within Progressive Web Apps (PWAs). Offline caching enhances user experience by ensuring that applications remain functional without a network connection.

2. Key Concepts

• Service Workers: Scripts that run in the background and manage caching.
• Cache API: Allows you to store and retrieve network requests and responses.
• IndexedDB: A low-level API for client-side storage of significant amounts of structured data.

3. Caching Strategies

3.1 Cache First Strategy

This strategy prioritizes cached content over network requests.

3.2 Network First Strategy

This strategy attempts to fetch resources from the network first and falls back to the cache if offline.

3.3 Stale While Revalidate Strategy

This strategy serves cached content and simultaneously updates the cache in the background.

4. Best Practices

• Ensure your service worker is registered correctly.
• Use cache versioning to manage updates.
• Optimize cache size to prevent exceeding storage limits.
• Implement fallback strategies for handling offline scenarios.

5. Code Examples

Service Worker Setup

self.addEventListener('install', event => {
    event.waitUntil(
        caches.open('v1').then(cache => {
            return cache.addAll([
                '/',
                '/index.html',
                '/styles.css',
                '/script.js'
            ]);
        })
    );
});
                

Fetch Event Handling

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

6. FAQ