Extension required when moduleResolution=bundler and imports/exports used #63157
Description
🔎 Search Terms
file extension bundler imports export
🕗 Version & Regression Information
- This is the behavior in every version I tried (6.0.0-dev.20260218, 5.9.3, 5.6.2), and I reviewed the FAQ for entries about common-bugs-that-arent-bugs
⏯ Playground Link
No response
💻 Code
with moduleResolution=bundler
src/example.ts
import internalFoo from '#src/imported-file'; // fails unless ".js" is added
import externalFoo from 'ts-repro/imported-file'; // fails unless ".js" is added
import relativeFoo from './imported-file'; // works
console.log(internalFoo, externalFoo, relativeFoo);src/imported-file.ts
export default 'foo';tsconfig.json
{
"compilerOptions": {
"noEmit": true,
"target": "ES2022",
"module": "ESNext",
"moduleResolution": "bundler",
},
"include": ["src/**/*.ts"]
}package.json
{
"name": "ts-repro",
"version": "1.0.0",
"scripts": {
"check": "tsc"
},
"imports": {
"#src/*": "./src/*"
},
"exports": {
"./*": "./src/*"
},
"packageManager": "pnpm@10.22.0",
"devDependencies": {
"typescript": "6.0.0-dev.20260218"
}
}🙁 Actual behavior
pnpm check
> ts-repro@1.0.0 check /home/polson/drw/ts-repro
> tsc
src/example.ts:1:25 - error TS2307: Cannot find module '#src/imported-file' or its corresponding type declarations.
1 import internalFoo from '#src/imported-file';
~~~~~~~~~~~~~~~~~~~~
src/example.ts:2:25 - error TS2307: Cannot find module 'ts-repro/imported-file' or its corresponding type declarations.
2 import externalFoo from 'ts-repro/imported-file';
~~~~~~~~~~~~~~~~~~~~~~~~
Found 2 errors in the same file, starting at: src/example.ts:1
🙂 Expected behavior
tsc passes, which aligns with the behavior of vite build:
index.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>ts-repro</title>
</head>
<body>
<script type="module" src="/src/example.ts"></script>
</body>
</html>
</code>vite.config.mts
import { defineConfig } from 'vite';
export default defineConfig({});Additional information about the issue
The reason why I care is that I'm writing a react app with a mixture of .ts and .tsx files, so I can't just use "./src/*.ts" because tsx files won't match
Typescript docs
- According to the docs: "--moduleResolution bundler attempts to model the module resolution behavior common to most JavaScript bundlers". There is clearly a divergence between the bundler behavior and the typescript behavior
- The module resolution docs say that "Like node16 and nodenext, this mode supports package.json "imports" and "exports", but unlike the Node.js resolution modes, bundler never requires file extensions on relative paths in imports", which is wonderfully ambiguous about this edge case
- I found one doc that says
TypeScript’s implementation for resolving a module specifier through "exports" to a file path follows Node.js exactly, which seems to agree that the "actual behavior" described above is the desired behavior, but this seems really weird. I would expect it to match the bundler behavior when moduleResolution=bundler