[Harsh Vardhan Chauhan (1-DARK)]

Fixes #65167

Summary

Adds a fourslash regression test showing that the native language service already uses JSDoc @this and @param types in JS files for completions, hover, and signature help.

This is a test-only change. It doesn't change any behavior.

Background

#65167 reports that the native LS treats JSDoc @this/@param types as any for completions, hover, and signature help, even though the checker uses them correctly.

The repro in the issue sets @allowJs/@checkJs but has no // @filename: /x.js, so the content isn't treated as JS. In TS files, JSDoc @this/@param types aren't used for typing, so the reported any (and no member completions) is expected there.

With an actual .js file, every scenario from the issue and its follow-up comments already works on main.

Test

tsc/internal/fourslash/tests/jsdocThisAndParamTypesInJs_test.go, in /a.js with @allowJs + @checkJs:

/**
 * @this {{ id: string, click: () => void }}
 * @param {{ name: string }} p
 */
function h(p) {
  this./*thisCompletions*/;
  p./*paramCompletions*/;
}

/**
 * @param {string} a
 * @param {number} b
 */
function f(a, b) {}
f(/*signatureHelp*/);

Feature	Marker	Expected
Completions (@this)	this.	exactly click, id
Completions (@param)	p.	exactly name
Hover (@param)	p	(parameter) p: { name: string; }
Signature help (@param)	f(	f(a: string, b: number): void

To confirm the test catches the reported failure, I changed the file to /a.ts. The test then fails with the same error as the issue (At marker 'thisCompletions': Expected completion list but got nil.).

Checklist

• There is an associated issue in the Backlog milestone (Native LS: JSDoc @this / @param types are any for hover & completions (checker OK) #65167)
• Code is up-to-date with the main branch
• Tests pass (go test ./internal/fourslash/...; test-only change, so I didn't run the full npx hereby test suite)
• npx hereby lint passes
• npx hereby check:format passes
• There are new or updated tests validating the change

[typescript-automation]

This PR doesn't have any linked issues. Please open an issue that references this PR. From there we can discuss and prioritise.

[Copilot]

🟢 Approval recommended

No active review issues are reported for the added JavaScript JSDoc regression coverage.

No open issues 🎉

What changed in this PR

Adds regression coverage related to #65167 for JSDoc types in the native language server. The test explicitly uses a JavaScript file and introduces no production behavior changes.

Changes:

• Checks @this and @param member completions.
• Verifies parameter hover types and function signature help.

File	Description
tsc/​internal/​fourslash/​tests/​jsdocThisAndParamTypesInJs_test.go	Adds a fourslash test for JSDoc-based completions, hover, and signature help in JavaScript.

_{Review effort: Balanced}