Feature request: Ignore JS files when generating declarations

Suggestion

🔍 Search Terms

ignore js files generate declarations

✅ 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

The docs for the declaration tsconfig option say:

Generate .d.ts files for every TypeScript or JavaScript file inside your project.

What if it was just TS files, and JS files were ignored?

📃 Motivating Example

I'm getting a bunch of declaration emit errors in JS files. I would rather just ignore them; I'll be converting them to TS eventually and will get higher fidelity. But until then, I'd rather not try to figure out how to annotate the JS to solve this problem.

💻 Use Cases

I'm getting errors that I don't care about.

No implementation files or tests are named. Start by tracing the declaration tsconfig option through the TypeScript compiler and its declaration-emit tests; done means JavaScript files are excluded from declaration generation while TypeScript files continue to emit declarations.