[tsserver] add support to fetch symbol references from only the current file.

🔍 Search Terms

Hey.
it will be awesome if the "references" command can only get references of a symbol at position (x,y) but only inside the current file.

✅ Viability Checklist

• 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 isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
• This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals

⭐ Suggestion

this can be added using currentFileOnly?: boolean; (like that inside interface NavtoRequestArgs).

📃 Motivating Example

i use it mainly for rewriting javascript files (usually obfuscated ones), so for each symbol i need to get all references but only for the currently opened file, so i wish there was a flag for it. as i thought it will be more performant (i.e. instead of searching references all across the project, if we restricted it to the current file - by a flag in a the request - then it can be more performant due to reduced search space?)

💻 Use Cases

1. What do you want to use this for?

• rewriting js files accurately.

3. What shortcomings exist with current approaches?

• performance issues.

5. What workarounds are you using in the meantime?

• requesting references then filtering them if the ref['file'] key is the same as that supplied in references request. however, i think tsserver can be more performant than this approach.

Start by tracing the tsserver references request and compare its arguments with NavtoRequestArgs, which the issue cites as a precedent. Determine the request and response paths affected, then add and validate a current-file-only option so references can be limited to the supplied file without changing existing behavior.