`svelte-check` ignoring `jsconfig.json`'s `exclude` option

[kierangilliam]

svelte-check will not use a jsconfig.json's exclude option to ignore .svelte files.

Please see this to reproduce.

If you open this project in vscode and navigate to jsconfig.json you'll see that src/routes is excluded from type checking. This is confirmed to work for *.js files (see src/routes/in-route.js). However, as seen in src/routes/index.svelte, the language server will ignore the exclusion of this folder and perform type checking.

[jasonlyu123]

Typescript's tsserver has a concept called inferred project. It seems like if according to the include and exclude the file doesn't belong to any config file, It would fall into this inferred project category. So it's not typescript respect the config and doesn't type check the in-route.js file. It's that the jsconfig.json doesn't apply to that file. If you enable the strict mode in the jsconfig.json and has a variable with string | undefined type in both in-route.js and in-lib.js.

/**@type {string | undefined}*/
let a;

Hover over it in the editor and you'll see that in-route.js shows let a: string while in-lib.js shows let a: string | undefined.

So technically the difference is that we have a different approach to determine whether the file belongs to the jsconfig/tsconfig.

But I don't know if we can make it consistent with the tsserver. Historically, setting svelte files in the include config doesn't do anything. When analysing the config file, typescript won't tell us if the file belongs to the config file. So we only check if the file is in the directory where the config is. Although including the svelte file in the include does include the file now. But there should be a lot of people who don't have svelte files in the include. This means if we change this behaviour it'll be a breaking change.

And by the way, your exclude actually doesn't do anything. As the route path is not in the include. You can see the explanation in the typescript doc

[kierangilliam]

Thanks for your explanation. So, the best workaround to this issue would be to do the following in .vscode/settings.json, yeah?

{
	"svelte.plugin.typescript.diagnostics.enable": false
}

But there should be a lot of people who don't have svelte files in the include. This means if we change this behaviour it'll be a breaking change.

Yeah I agree that wouldn't be ideal. Instead of requiring people to use include, is it possible to grab the project's tsconfig/jsconfig's exclude and ensure those files are also ignored?

And by the way, your exclude actually doesn't do anything. As the route path is not in the include. You can see the explanation in the typescript doc

Also thanks for this; I didn't realize! The example is updated to correct for this.