Absolute import paths, especially on Windows, must be `file://` URLs when using ESM. Otherwise, Windows drive letters (e.g., `C:`) would be interpreted as a protocol instead of a drive letter when performing the import.
With the Angular CLI currently being a CommonJS package, this change uses a dynamic import to load `@angular/service-worker/config` which may be ESM. CommonJS code can load ESM code via a dynamic import. Unfortunately, TypeScript will currently, unconditionally downlevel dynamic import into a require call. require calls cannot load ESM code and will result in a runtime error. To workaround this, a Function constructor is used to prevent TypeScript from changing the dynamic import. Once TypeScript provides support for keeping the dynamic import this workaround can be dropped and replaced with a standard dynamic import.
Since #20518, the generation of the ServiceWorker configuration has been
broken on Windows. The reason is the use of `path.posix.*` methods on
non-POSIX paths, resulting in broken paths. I.e. we ended up with
something like the following:
```js
path.posix.relative('C:\\foo', 'C:\\foo\\bar/baz');
// Expected result: `bar/baz`
// Actual result: `../C:\\foo\\bar/baz`
```
This caused the config generator to fail to find any files and thus fail
to populate the config with cacheable assets.
This commit fixes this by using platform-specific `path.*` methods for
path manipulation and manually normalizing the path separators before
returning the results.
Fixes#20894
All TypeScript files have been updated to pass the new eslint-based linting checks. eslint compatible disabling comments have also been added in place of the previous tslint comments.
With the minimum version of Node.js now set to v12, the promise fs API can now be leveraged within the tooling.
This change also uses `copyFile` (with copy-on-write where available) to setup the the service worker files as well a streaming APIs to generate service worker hashes. Both of which improves performance and reduces memory usage.
The virtualfs Host was only used for exist and directory checks during asset and file replacement option normalization within the browser and dev-server builders.
