Unable to define a `.js` file as ServiceWorkerGlobalScope

[wilsonpage]

When a .js file is a service-worker, there's no way to define its scope/self/this as ServiceWorkerGlobalScope. This means service-worker only global APIs like self.skipWaiting() are undefined and fail Typescript's checkjs run.

Minimal test-case

https://github.com/wilsonpage/vscode-scope-test-case

Twitter thread w/ @DanielRosenwasser

https://twitter.com/drosenwasser/status/1113905694028132352

[saschanaz]

#1034 added serviceworker lib and is available on TS 4.4

@github-actions close

[github-actions]

Closing because @saschanaz is one of the code-owners of this repository.