SW Update Manager

Copyright 2018 Caleb Evans
Released under the MIT license

SW Update Manager is a front-end package that allows you to detect updates to your service worker and prompt the user to update with a notification.

This project has now hit v1.0, so the API is now stable.

Getting Started

1. Load the script into your application

First, you need to load the SW Update Manager script into the front-end portion of your application. You can do this via <script> tag or through your build process.

<script src="node_modules/sw-update-manager/sw-update-manager.js"></script>

var SWUpdateManager = require('sw-update-manager');

import SWUpdateManager from 'sw-update-manager';

2. Add front-end JS

In your front-end JavaScript, you will need to initialize a new SWUpdateManager instance and ensure it is accessible by the code that spawns the update notification.

if (navigator.serviceWorker) {
  let serviceWorker = navigator.serviceWorker.register('service-worker.js');
  this.updateManager = new SWUpdateManager(serviceWorker);
  // Use the optional updateAvailable hook to re-render the UI (or run any other
  // necessary code) when an update is available
  this.updateManager.on('updateAvailable', () => this.render());
  // You must explicitly tell SW Update Manager when to check for updates to the
  // service worker
  this.updateManager.checkForUpdates();
}

You can use the isUpdateAvailable property on your SWUpdateManager object to decide when to display the update notification.

<div className={`update-notification ${this.updateManager.isUpdateAvailable ? 'visible': 'hidden'}`}></div>

Whenever you decide to trigger the service worker update, call the update() method on your SWUpdateManager object. You can call update() however you want, but for a simple user experience, bind a click event to the update notification you show to the user (a long as you instruct the user to click the notification to update).

<div className='update-notification' onclick={() => this.updateManager.update()}></div>

All of these code examples are using React/JSX because the syntax is familiar to many developers. However, you could effortlessly use any of these features with another library or in vanilla JavaScript.

3. Listen for update requests to your service worker

The final step in configuring SW Update Manager is to listen for events from the service worker itself.

// When an update to the service worker is detected, the front end will request
// that the service worker be updated immediately; listen for that request here
self.addEventListener('message', (event) => {
  if (!event.data) {
    return;
  }
  if (event.data.updateManagerEvent === 'update') {
    self.skipWaiting();
  }
});

Other API features

Controlling update behavior

If you'd like to stop SW Update Manager from reloading the page automatically when calling update(), set reloadOnUpdate to false. You can do this on initialization on the update manager, or afterwards.

this.updateManager = new SWUpdateManager(serviceWorker, {
  reloadOnUpdate: false
});

this.updateManager = new SWUpdateManager(serviceWorker);
this.updateManager.reloadOnUpdate = false;

You can also run your own code before the actual update takes place by listening for the update event.

// The page will still reload automatically after this callback fires, unless
// you set reloadOnUpdate to false as described above
this.updateManager.on('update', () => {
  localStorage.setItem('lastUpdateTime', Date.now());
});

The update event fires only when the service worker is actually able to be updated. Calling the update() method a second time will not fire the event callbacks again, nor will the callbacks fire at all if the service worker is missing the aforementioned listener code.