[feat] allow to disable service worker auto inject

[SomaticIT]

This PR allows to disable the automatic injection of the service worker.
This allows developpers to code a custom logic to register service workers.

It is particularly useful when using workbox to manage the service worker.

Workaround

As a workaround, I actually use a script that I run after svelte-kit build to strip the injected service worker from index.html but it only work for SPA builds. In SSR environments, a custom hook may be able to strip it.

But it's not a viable solution since it can break anytime the injected code is changed on the svelte-kit side.

Usage

In your svelte.config.js, you just have to set the following option:

const config = {
  // ... your config
  serviceWorker: {
    inject: false
  }
};

Fixes

• Service worker have a scope fixed at build time #922 (you can specify the scope manually)
• Provide the "register" object returned by navigator.serviceWorker.register #1749 (you can get the registration)
• Disable service-worker.js selectively on page_config #2367 (you can set the scope to ignore some parts of the site)
• Provide workbox integration or documentation #2660 (we can easily register workbox manually)

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests

• Run the tests with pnpm test and lint the project with pnpm lint and pnpm check

Changesets

• If your PR makes a change that should be noted in one or more packages' changelogs, generate a changeset by running pnpx changeset and following the prompts. All changesets should be patch until SvelteKit 1.0

Todo

• Write documentation
• Add a test case
• Once validated, add changeset

[changeset-bot]

🦋 Changeset detected

Latest commit: c456bef

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@sveltejs/kit	Patch

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[SomaticIT]

I added documentation and test.

The CI fails on windows due to a timing issue (not related with this PR).
Maybe a contributor can rerun the windows checks.

I think this is ready for review.

[benmccann]

This generally seems reasonable to me and similar to #2281. My main question for the other maintainers would be about what we should call the option name

[SomaticIT]

@benmccann, thank you for your reply.

1/ Regarding #2281, you're right, I found this PR after implementing the feature. However, this PR takes a simpler approach: if you want to customize the service worker behavior, just disable automatic injection and do what you want 😁. It means less impact on the kit code (only 3 lines impacted) and less maintenance.

2/ Regarding the option name, I think there are two possibilities:

• inject: to explain the fact that the code is injected in your page. This was my first choice but I'm open to change
• register: to explain the behavior of the code which actually register the service worker.

Let met know your preference, I will adapt the PR to your choice.

[SomaticIT]

Hello,

I would like to know if it's possible to review this PR?
It is a very simple modification (3 lines of code impacted).

I'm using a custom script to workaround this issue but I'm creating new projects every week and it will become very hard to maintain in the future.

Thank you in advance

[Rich-Harris]

Thank you! I renamed the option to register, moved the test app (sw-inject -> options-2, since it serves the same function as options and would have been combined if the options under test weren't incompatible) and added a changeset

[SomaticIT]

Thank you for your intervention!
I totally agree with all your changes.