Add default script language completion

[devmattrick]

This PR fixes #1262 by adding a new configuration option: svelte.plugin.svelte.defaultScriptLanguage. This option can either be none or ts, which will configure Svelte VSCode to use <script> or <script lang="ts"> respectively when generating new script tags on auto import.

Let me know if you'd like any changes. Thanks!

[jasonlyu123]

Looks good to me 👍

Can you also document the config to the README?

[dummdidumm]

Should we put this inside completions? Like "svelte.plugin.svelte.completions.defaultScriptLanguage"? @jasonlyu123 what do you think?

[jasonlyu123]

Hmm. It is also being used in the code action. if we want to further organize it. Maybe the name needs to be more generic. Maybe something like suggest or preferences?

[dummdidumm]

Oh right, it's also part of the code action. In that case, never mind 😄 My fear is that people would mistake this as something like "if I set this I don't need to write <script lang="ts"> at all" (like the deprecated and discouraged default language of svelte preprocess).

[RemyRylan]

Thanks @devmattrick for getting this together. I just wanted to ask before a maintainer here merges: is this something that should instead go in svelte.config.js?

I see this issue #422, would it be more straightforward to use that method instead?

// svelte.config.js
export default {
  preprocess: [
    autoPreprocess({
      defaults: { script: 'typescript' },
    }),
  ],
};

Does the VS Code extension pickup your svelte.config.js file?

[dummdidumm]

The config you mention is deprecated and discouraged. Problem is that not all tooling can reliably read the config, and there's also syntax highlighting limitations - as a result you get all kinds if weird behavior. This PR should only be about adding lang="ts" during a auto import or code action which creates a script tag, which is an editor-only feature so it shouldn't be part of svelte.config.js

[RemyRylan]

@dummdidumm got it, thank you!

[qwabra]

.vscode/settings.json

{
	"svelte.plugin.svelte.defaultScriptLanguage": "ts"
}

does not work?!

expexted <script lang="ts"></script>
instead <script></script>
it is right?

[jasonlyu123]

nope. This PR is for the script tag created when there's an auto-import.

<C

to

<script lang="ts">
  import Component from 'path/to/Component.svelte'
</script>

<Component

[qwabra]

"an auto-import" hmm.

what about snippets, is that possible by Svelte config?