What are the three main phases in a service worker's lifecycle?

Question

ICSM Computer · Answer

The three main phases in a 
Service Worker's lifecycle are:
1. Registration
This is when your web page tells the browser that it wants to use a service worker.Done using navigator.serviceWorker.register('/service-worker.js').
Code Example:
navigator.serviceWorker.register('/service-worker.js')
  .then(reg =andgt; console.log('Service Worker registered:', reg));
2. Installation
The browser downloads the service worker script and triggers the
install event.This is where you typically cache static assets (HTML, CSS, JS, etc.) needed for offline use.
Key Event:
self.addEventListener('install', event =andgt; {
  console.log('Service Worker installing...');
  // Cache files here
});
Note: If the install fails, the service worker is discarded.
3. Activation
After successful installation, the service worker enters the activate phase.This is a good time to clean up old caches or migrate data from a previous version.
Key Event:
self.addEventListener('activate', event =andgt; {
  console.log('Service Worker activating...');
  // Delete old caches or update DB
});
Once activated:
The service worker starts controlling pages (if eligible).The fetch event listener can now intercept network requests.
Bonus: Waiting Phase (Optional Middle State)
Between installation and activation, a service worker may enter a waiting state if an older version is still controlling pages. You can manually trigger it to take control using
skipWaiting().
self.skipWaiting(); // Forces activation immediately
Summary Table
Phase
Triggered When...
Common Tasks
Register
App requests registration
Starts the lifecycle
Install
New service worker is downloaded
Cache essential assets
Activate
Installation succeeds
Clean up old cache, claim clients
and

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What are the three main phases in a service worker's lifecycle?

ICSM Computer

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1 Answers

1. Registration

2. Installation

3. Activation

Bonus: Waiting Phase (Optional Middle State)

Summary Table

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Phase	Triggered When...	Common Tasks
Register	App requests registration	Starts the lifecycle
Install	New service worker is downloaded	Cache essential assets
Activate	Installation succeeds	Clean up old cache, claim clients