# Astro SW

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Use your own authored [service worker](https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API) with Astro.

The integration accepts the path to your service worker and automatically injects dynamic variables such as `__assets` generated by Astro for caching.

It works on all Astro output options: `static`, `server`, or `hybrid`, and lets developers retain the flexibility for various [caching strategies](https://developer.chrome.com/docs/workbox/caching-strategies-overview/).

## Installation

In your [Astro](https://astro.build) project:

```bash
# if using npm
$ npm i -D @ayco/astro-sw

# if using pnpm
$ pnpm add -D @ayco/astro-sw
```

## Minimal Usage

Here's an example `astro.config.mjs` file:

```js
import { defineConfig } from "astro/config";
import serviceWorker from "@ayco/astro-sw";

export default defineConfig({
  integrations: [
    serviceWorker({
      path: "./src/sw.ts",
    }),
  ],
});
```

For more options available, see the [API](#api).

## TypeScript support

We use `esbuild` to resolve service worker `imports` and build TS files! You can customize the build options by providing it to the `esbuild` configuration property.

```js
import { defineConfig } from "astro/config";
import serviceWorker from "@ayco/astro-sw";

export default defineConfig({
  integrations: [
    serviceWorker({
      path: "./src/sw.ts",
      esbuild: {
        minify: true,
      },
    }),
  ],
});
```

## Injected variables

The most important variable your service worker will have access to is `__assets`, which contains all routes and public assets that Astro includes in your build. Additionally, you will also get `__prefix` and `__version` you can use for naming & invalidating your Cache storage (useful for debugging purposes).

## eslint globals

Because of the injected variables not being defined in your script, you might get `eslint` errors for the undefined variables when you have the `no-undef` rule. You can use our exported `globals` object in your eslint config as follows:

```js
import astroSwGlobals from "@ayco/astro-sw/globals";

export default [
  {
    languageOptions: {
      globals: {
        ...astroSwGlobals,
      },
    },
  },
  // add more generic rule sets here, such as:
  // jsPlugin.configs.recommended,
];
```

## Registration Hooks

Hooks are provided for adding custom logic that triggers in various service worker registration events.

The following properties are available for the `registrationHooks` configuration:

1. `installing` - when the registration is 'installing'
1. `waiting` - when the registration is 'waiting'
1. `active` - when the registration is 'active'
1. `error` - when the registration throws an error
1. `unsupported` - when the service workers are unsupported
1. `afterRegistration` - after the registration succeeds

```js
import { defineConfig } from "astro/config";
import serviceWorker from "@ayco/astro-sw";

export default defineConfig({
  integrations: [
    serviceWorker({
      path: "./src/sw.ts",
      registrationHooks: {
        afterRegistration: async () => {
          const sw = await navigator.serviceWorker.getRegistration();
          console.log(">>> registrered", sw);
        },
        installing: () => console.log("installing..."),
        waiting: () => console.log("waiting..."),
        active: () => console.log("active..."),
        error: (error) => console.error(error),
        unsupported: () => console.log(":("),
      },
    }),
  ],
});
```

## API

The integration accepts a configuration object with the following properties

| property            | type                                           | required? | notes                                                                                                                                           |
| ------------------- | ---------------------------------------------- | --------- | ----------------------------------------------------------------------------------------------------------------------------------------------- |
| path                | string                                         | required  | path to your _own_ service worker script; no surprises & easy debugging                                                                         |
| assetCachePrefix    | string                                         | optional  | cache storage name prefix                                                                                                                       |
| assetCacheVersionID | string                                         | optional  | cache storage name versioning; by default, a random UUID is used                                                                                |
| customRoutes        | string[]                                       | optional  | list of custom routes you want to be cached. Beware that non-existent routes that result to HTTP Error404 will cause the service worker to fail |
| excludeRoutes       | string[]                                       | optional  | list of routes you want to be ignored/removed from assets                                                                                       |
| logAssets           | boolean                                        | optional  | set to see a list of the assets found; defaults to false                                                                                        |
| esbuild             | [BuildOptions](https://esbuild.github.io/api/) | optional  | custom build options for your service worker script                                                                                             |
| registrationHooks   | object                                         | optional  | provide callbacks for various registration events; see section on [Registration Hooks](#registration-hooks)                                     |

## Background

This integration was developed to support the Caching strategy needs of [Cozy](https://cozy.ayco.io) -- the modern reading companion for the Web. You can find [an example service worker in the repository](https://github.com/ayoayco/Cozy/blob/main/src/sw.mjs).