Service Worker Basics

Introduction

Service Workers are a key component of Progressive Web Apps (PWAs) that enable features like offline capabilities, push notifications, and background synchronization. They act as a proxy between the web application and the network, allowing developers to control network requests and cache responses.

What is a Service Worker?

A Service Worker is a script that the browser runs in the background, separate from a web page. This script can intercept network requests and modify responses, allowing for enhanced performance and offline access.

How Service Workers Work

1. Install: The Service Worker is installed in the browser.
2. Activate: Once installed, the Service Worker is activated.
3. Fetch: The Service Worker can now intercept requests and serve cached responses.

self.addEventListener('install', function(event) {
    console.log('Service Worker installing...');
});

self.addEventListener('activate', function(event) {
    console.log('Service Worker activated!');
});

self.addEventListener('fetch', function(event) {
    console.log('Fetching:', event.request.url);
});
            

Registering a Service Worker

To register a Service Worker, use the following code in your main JavaScript file:

if ('serviceWorker' in navigator) {
    window.addEventListener('load', function() {
        navigator.serviceWorker.register('/sw.js')
        .then(function(registration) {
            console.log('Service Worker registered with scope:', registration.scope);
        })
        .catch(function(error) {
            console.log('Service Worker registration failed:', error);
        });
    });
}
            

Best Practices

• Always use HTTPS for your Service Worker.
• Cache only the necessary resources to improve loading speed.
• Update the Service Worker regularly to handle new features or changes.
• Test your Service Worker in different scenarios (offline, slow network).

FAQ