Add input option to plugin-svelte

[firefish5000]

Changes

Adds an input option to plugin-svelte that modifies resolve.input. Enables non-standard file extensions such as .svx to be used

Testing

Roughly copied the related tests from plugin-babel. Had issues getting test to run properly locally, so opening the PR a bit early to see the results.

Docs

Roughly copied related docs from plugin-babel.

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[firefish5000]

Test Passed. Ready for review

[canadaduane]

I use svelte, but haven't heard of the svx convention before. Out of curiosity, how common is this?

[firefish5000]

@canadaduane This PR adds ability to modify the file extensions we run on, primarily to add things in addition to .svelte. It add feature parity with the rollup and webpack svelte plugins.

Overriding extensions for plain svelte files is not a standard convention, but a couple of popular preprocessors and plugins do this. Namely the markdown preprocessor for svelte, pngwn/MDsveX, which uses .svx as its convention (but can be made to run on normal .svelte files as well)
There is also the storybook replacement, rixo/svench which runs on .svench (and also recommends using mdsvex for documentation).

Its worth noting that for mdsvex, using another file extension is sort of required since it treats the entire file as html enabled markdown without checking/needing a lang="md" attribute. Meaning <p> *words* <p> will italicize, something you probably dont want in a normal svelte file

[FredKSchott]

LGTM!

[firefish5000]

Thinking about why he asked made me realize I put ['.svelte','.svx'] into the recommendation of the error output instead of just the default value ['.svelte'], as I did in the documentation. This was primarily to show it was an array of file extensions and to sort of to match what the babel plugin threw, but I can see how it could be confusing. Probably would have been better to just recommend the default

[FredKSchott]

I think it's fine as-is. It would only show that to the user who's playing around with the input setting, so it's not necessarily the "default" user who would see that message.

[canadaduane]

Thanks, that makes more sense now.

…

On Sun, Oct 18, 2020, 1:35 AM Fred K. Schott ***@***.***> wrote: I think it's fine as-is. It would only show that to the user who's playing around with the input setting, so it's not necessarily the "default" user who would see that message. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#1347 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAABAP73F6UJPLUKDLL5BTSLKLEZANCNFSM4SUTFRXA> .

[techniq]

Could this be defaulted to the extensions value in svelte.config.js to cut down on duplication?

• https://github.com/sveltejs/rollup-plugin-svelte#usage

[firefish5000]

@techniq While I also use extensions in my svelte.config.js (since that is the name of the rollup plugin's option, and I need to keep my svelte.preprocess cli in sync with my builder/bundler), I believe the field is non-standard and not recommended in the language-tools docs. I am doubtful it will become a standard as well since iirc, webpack uses a different mechanism for matching files with loaders. (meaning rollup plugin is the only thing that has a extensions field, and everything else uses a different name and/or method for matching svelte files)