serviceworker-webpack-plugin

Simplifies creation of a service worker to serve your webpack bundles.

Installation

npm install serviceworker-webpack-plugin

The problem solved

When building a service worker, you probably want to cache all your assets during the install phase. But in order to do so, you need their names. That's not simple when you are using Webpack:

• The assets names are non-deterministic when taking advantage of the long term caching.
• The assets list can even evolve over time as you add splitting points or more resources.
• You want to be able to use your service worker with the dev-server mode of Webpack.
• You want to keep the build process as simple as possible.

Setup

1. Add the plugin to your webpack config

import ServiceWorkerWebpackPlugin from 'serviceworker-webpack-plugin';

...

  plugins: [
    new ServiceWorkerWebpackPlugin({
      entry: path.join(__dirname, 'src/sw.js'),
    }),
  ],

2. Register the service worker in your main JS thread

import runtime from 'serviceworker-webpack-plugin/lib/runtime';

if ('serviceWorker' in navigator) {
  const registration = runtime.register();
}

3. Write your own sw.js

You can now use the global serviceWorkerOption variable in your sw.js. E.g. In our example this object looks like:

{
  assets: [
    './main.256334452761ef349e91.js',
  ],
}

Simple example

You can have a look at the /docs folder if you need a full working example.

API

ServiceWorkerWebpackPlugin(options)

• options
• entry, required, string: Path to the actual service worker implementation.
• filename, string, default 'sw.js': Relative (from the webpack's config output.path) output path for emitted script.
• excludes, array, default ['**/.*', '**/*.map']: Exclude matched assets from being added to the serviceWorkerOption.assets variable. (Blacklist)
• includes, array, default ['**/*']: Include matched assets added to the serviceWorkerOption.assets variable. (Whitelist)
• publicPath, string, default '/': Specifies the public URL address of the output files when referenced in a browser. We use this value to load the service worker over the network.
• template, function, default noop: This callback function can be used to inject statically generated service worker. It's taking a serviceWorkerOption argument and must return a promise.
• transformOptions, function: This callback function receives a raw serviceWorkerOption argument. The jsonStats key contains all the webpack build information.

runtime(options)

• options: That's forwarded to the options argument of the ServiceWorkerContainer.register() function.

Credit

• The offline-plugin package was a great source of inspiration.
• The html-webpack-plugin package was also really helpful.

Why simply not use the offline-plugin?

I wouldn't have been able to write this plugin without the offline-plugin project. Thanks @NekR for sharing it!

Still, soon after using it, I realized that it wasn't what I was looking for.

• The abstraction provided was too high. (I needed to build some custom fetch logic.)
• It was making me, even more, dependent on Webpack. (What if later, I want to switch to another build system?)

Hence, I decided to change the approach and created this thin layer on top of Webpack to solve the assets name issue. Nothing more.

If you don't care about my two issues with offline-plugin then you don't need to use this package, offline-plugin is great.

The specs

• Service Workers

License

MIT