snowpack-service-worker-assets

This is a very simple Snowpack plugin to help you if you are rolling your own service worker.

A typical service worker has the following lines to cache application assets (copied from MDN article):

self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open('v1').then((cache) => {
      return cache.addAll([
        './sw-test/',
        './sw-test/index.html',
        './sw-test/style.css',
        './sw-test/app.js',
        './sw-test/image-list.js',
        './sw-test/star-wars-logo.jpg',
        './sw-test/gallery/',
        './sw-test/gallery/bountyHunters.jpg',
        './sw-test/gallery/myLittleVader.jpg',
        './sw-test/gallery/snowTroopers.jpg'
      ]);
    })
  );
});

When you have numerous files, or the filenames are determined at build time (perhaps because you use snowpack-plugin-hash for example) adding these filenames to the addAll array becomes difficult.

This plugin automates the process. It runs after your bundler and looks for assets in your build directory that match a pattern. These filenames are injected in your service worker using simple string replacement.

Install

npm i --save-dev snowpack-service-worker-assets

or:

yarn add -d snowpack-service-worker-assets

Usage

Add snowpack-service-worker-assets to the end of your snowpack plugins.

plugins: [
	...plugins
	[
		'snowpack-service-worker-assets',
		{
			patterns: ['**/*', '!sw.js', '!**/*.map'],	//required
			worker: 'sw.js',	//required
			replace: "'snowpack-service-worker-assets'"	// optional, default value shown
		}
	]
],

There are three options:

• patterns tells the plugin which files to add to the service worker. These patterns are fed straight to fast-glob so refer to that project for help on patterns. The file patterns are relative to your snowpack build directory.
• worker is the path (relative to build dir) of the service worker.
• replace is the string that the plugin will seek to replace in the service worker file. Note the nested quotes in the example above. Your service worker needs to include that string:

self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open('v1').then((cache) => {
      return cache.addAll([
        'snowpack-service-worker-assets'
      ]);
    })
  );
});

License

MIT