TS: Named export from module script not recognized

Describe the bug Importing named exports from <script context='module'> returns an error saying:

Module ‘“*.svelte”’ has no exported member …

The image is from a test file that imports both the component and the helper method

The svelte component looks like this:

<script context="module" lang="ts">
export const reverseValue = (min: number, max: number) => (
  scale: number,
): number => max - scale + min;
</script>

...

Typescript Config

{
  "extends": "@tsconfig/svelte/tsconfig.json",
  "compilerOptions": {
    "baseUrl": ".",
    "paths": {"*": ["*", "typings/*"]},
    "noImplicitAny": true,
    "emitDecoratorMetadata": true,
    "skipLibCheck": true,
    "experimentalDecorators": true,
    "esModuleInterop": true,
    "noImplicitReturns": true,
    "noUnusedParameters": true,
    "strictFunctionTypes": true,
    "strictNullChecks": true,
    "types": ["jest", "chrome", "node"],
    "allowJs": true,
    "isolatedModules": false,
    "target": "ESNext",
    "allowSyntheticDefaultImports": true
  },
  "include": ["src/**/*.ts", "src/**/*.tsx", "src/**/.svelte", "typings/*.d.ts", "test/*.ts"],
  "exclude": ["node_modules"]
}

• Svelte: 3.24.1
• Svelte Preprocess: 4.2.1
• Svelte TS Config: 1.0.10
• Typescript: 4.0.2

Expected behavior The exports should be recognized

Severity Not severe. Just a small hindrance

[mrmckeb]

I’m not sure you want to learn from my code haha, but if you have any questions I’ll do my best to answer. Thanks for the shout-out @IgnusG.

The only note I’ll make is that Language Service plugins only run in IDEs, not during build-time. People have been asking for this change for a while, but the TypeScript team don’t seem convinced that it’s a good direction.

[jasonlyu123]

https://github.com/microsoft/TypeScript/wiki/Writing-a-Language-Service-Plugin

Seems like angular language service use the plugin technique. We could probably learn something from their code 😂.