svelte:options customElement type issue

[m-poh]

Describe the bug

When I use verbose configuration for custom elements, then I get unexpected typescript-related errors when running svelte-check.

Reproduction

<svelte:options
  customElement={{
    tag: "my-component",
    extend: (customElementConstructor) => {
      return class extends customElementConstructor {
        constructor() {
          super()
        }
      }
    },
  }} />

<script lang="ts"></script>

This gives Svelte: Parameter customElementConstructor implicitly has an any type.

Then i silence this with @ts-ignore:

<svelte:options
  customElement={{
    tag: "my-component",
    // @ts-ignore
    extend: (customElementConstructor) => {
      return class extends customElementConstructor {
        constructor() {
          super()
        }
      }
    },
  }} />

<script lang="ts"></script>

Then i extend the configuration for svelte:options with props:

<svelte:options
  customElement={{
    tag: "my-component",
    props: {
      stringValue: { type: "String" },
    },
    // @ts-ignore
    extend: (customElementConstructor) => {
      return class extends customElementConstructor {
        constructor() {
          super()
        }
      }
    },
  }} />

<script lang="ts">
  export let stringValue: string
  let anotherValue: number
</script>

which gives Type annotations can only be used in TypeScript files. (js) for both stringValue and anotherValue

Expected behaviour

no errors for both of the examples

System Info

• OS: Ubuntu
• IDE: IntelliJ IDEA
• svelte-check version: 3.6.9 / 3.8.5

Which package is the issue about?

svelte-check

Additional Information, eg. Screenshots

No response

[jasonlyu123]

The Type annotations can only be used in TypeScript files. (js) issue has the same reason with sveltejs/language-tools#2155 where the HTML parsing doesn't parse the option correctly so the lang="ts" doesn't get extracted. If you move svelte:options to be after the script tag it should work.

As for the type of the customElement, this needs adjustment with the type definition here therefore transferring. The HTMLProp type seems to override the customElment definition in the "svelte/elements". Probably can just remove the override since you can't add an option to the svelte:options so we don't need to support type enhancement for it.

[m-poh]

just to clarify, i think you meant customElementConstructor instead of customElement in "As for the type of the customElement"

[jasonlyu123]

Not really. The whole customElement option is not typed because it got overridden.