API: Expose a way to figure out the `scriptKind`

Suggestion

🔍 Search Terms

api scriptkind

✅ Viability Checklist

My suggestion meets these guidelines:

• This wouldn’t be a breaking change in existing TypeScript/JavaScript code
• This wouldn’t change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn’t a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript’s Design Goals.

⭐ Suggestion

It seems like at the moment the scriptKind property of SourceFile is marked as @internal, it would be nice if this was exposed in the public api.

https://github.com/microsoft/TypeScript/blob/a21024dbe7e79dc018e4193f27ecb66e0465b638/src/compiler/types.ts#L3802-L3804

📃 Motivating Example

I’d like to know if a SourceFile is of ScriptKind.JS, so that I can make specific modifications to .js files only. I could simply check if the SourceFile.fileName ends with .js. But I’d rather make use of the same logic that is used by TypeScript for checking if a file is a JavaScript file. That way I can be sure my application and TypeScript are on the same page of what is and isn’t a JavaScript file.

💻 Use Cases

I have written a basic transformer that makes several modifications to files in a project. And now I’d like to add // @ts-nocheck to all JavaScript files.

[RyanCavanaugh]

I don’t see an issue with exposing this, so if you or someone else end up needing this please give another ping and we can evaluate in more detail.

[sheetalkamat]

Not that i can think of…