Microsoft/TypeScript

Emitted declarations for JS file do not import a class if it's re-exported

Open

#61,718 opened on May 17, 2025

View on GitHub
 (1 comment) (0 reactions) (0 assignees)TypeScript (48,455 stars) (6,726 forks)batch import
BugDomain: Declaration EmitHelp Wanted

Description

🔎 Search Terms

import export class declarations

🕗 Version & Regression Information

This changed in PR #55472, commit 5ce34cafad, version 5.3.0-dev.20230829.

⏯ Playground Link

No response

💻 Code

index.js:

import { Something } from './something';
export { Something } from './something';

export const something = new Something();

something.ts (or something.js):

export class Something {}

tsconfig.json:

{
  "compilerOptions": {
    "checkJs": true,
    "declaration": true,
    "outDir": "dist"
  }
}

🙁 Actual behavior

The import of Something is missing in the emitted declarations file index.d.ts:

export { Something } from "./something";
export const something: Something;

🙂 Expected behavior

The import of Something should be included in the emitted declarations file index.d.ts:

export { Something } from "./something";
export const something: Something;
import { Something } from './something';

Additional information about the issue

The problem does not occur if

  • the file name is index.ts instead of index.js
  • export const something includes an explicit JSDoc type annotation (/** @type {Something} */)

Contributor guide

Tech stack
typescriptjavascript
Domain
toolingbuild systemdeveloper experience
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic TypeScript knowledgeUnderstanding of declaration files
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
35
Research direction
Investigate the declaration emitter's handling of JavaScript files when re exporting classes. Focus on the changes in PR #55472 (commit 5ce34cafad) which introduced this regression. Compare the behavior for `.ts` vs `.js` files in the emitter. Likely files: `src/compiler/emitter.ts` or `src/services/codefixes/importFixes.ts`. Check if the issue is in the logic that skips adding implicit imports for JS files.