node-builder: Always compile `.mts` to ESM #13693

jeffsee55 · 2025-08-07T22:31:16Z

When theres' no tsconfig & no "type": "module" we should still compile to ESM. The previous PR was just for .ts files, which may compile to CJS if there's no "type": "module", but for .mts we should never do that.

EDIT: this PR was dramatically simplified to just use nodenext when no tsconfig.json is found

… no tsconfig exists

changeset-bot · 2025-08-07T22:31:21Z

🦋 Changeset detected

Latest commit: 8c6d451

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
@vercel/hono	Patch
@vercel/node	Patch
vercel	Patch
@vercel/express	Patch

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packages/hono/test/unit/build.test.ts

…ith-no-tsconfig-are-always-3

packages/node/src/build.ts

packages/node/src/typescript.ts

Co-authored-by: Steven <steven@ceriously.com>

…flow-4690-fix-issue-where-ts-files-with-no-tsconfig-are-always-3

…nfig-are-always-3' of https://github.com/vercel/vercel into jeffsee/flow-4690-fix-issue-where-ts-files-with-no-tsconfig-are-always-3

packages/node/src/typescript.ts

Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>

vercel

Additional Comments:

packages/hono/test/fixtures/13-index-mts-no-tsconfig-node-no-module (lines NaN-NaN):

The test fixture directory is incorrectly numbered as "13", but there's already a "13-app-js-no-module" fixture, creating a duplicate number in the test suite.

View Details

📝 Patch Details

diff --git a/packages/hono/test/fixtures/13-index-mts-no-tsconfig-node-no-module/.gitignore b/packages/hono/test/fixtures/14-index-mts-no-tsconfig-node-no-module/.gitignore
similarity index 100%
rename from packages/hono/test/fixtures/13-index-mts-no-tsconfig-node-no-module/.gitignore
rename to packages/hono/test/fixtures/14-index-mts-no-tsconfig-node-no-module/.gitignore
diff --git a/packages/hono/test/fixtures/13-index-mts-no-tsconfig-node-no-module/index.mts b/packages/hono/test/fixtures/14-index-mts-no-tsconfig-node-no-module/index.mts
similarity index 100%
rename from packages/hono/test/fixtures/13-index-mts-no-tsconfig-node-no-module/index.mts
rename to packages/hono/test/fixtures/14-index-mts-no-tsconfig-node-no-module/index.mts
diff --git a/packages/hono/test/fixtures/13-index-mts-no-tsconfig-node-no-module/package-lock.json b/packages/hono/test/fixtures/14-index-mts-no-tsconfig-node-no-module/package-lock.json
similarity index 94%
rename from packages/hono/test/fixtures/13-index-mts-no-tsconfig-node-no-module/package-lock.json
rename to packages/hono/test/fixtures/14-index-mts-no-tsconfig-node-no-module/package-lock.json
index d41a96ae4..00c97e9fb 100644
--- a/packages/hono/test/fixtures/13-index-mts-no-tsconfig-node-no-module/package-lock.json
+++ b/packages/hono/test/fixtures/14-index-mts-no-tsconfig-node-no-module/package-lock.json
@@ -1,5 +1,5 @@
 {
-  "name": "13-index-mts-no-tsconfig-node-no-module",
+  "name": "14-index-mts-no-tsconfig-node-no-module",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
diff --git a/packages/hono/test/fixtures/13-index-mts-no-tsconfig-node-no-module/package.json b/packages/hono/test/fixtures/14-index-mts-no-tsconfig-node-no-module/package.json
similarity index 100%
rename from packages/hono/test/fixtures/13-index-mts-no-tsconfig-node-no-module/package.json
rename to packages/hono/test/fixtures/14-index-mts-no-tsconfig-node-no-module/package.json
diff --git a/packages/hono/test/unit/build.test.ts b/packages/hono/test/unit/build.test.ts
index e8ace8c2b..d37fa7a35 100644
--- a/packages/hono/test/unit/build.test.ts
+++ b/packages/hono/test/unit/build.test.ts
@@ -118,7 +118,7 @@ const fixtures = {
     handler: ['index.mjs'],
     moduleType: 'esm',
   },
-  '13-index-mts-no-tsconfig-node-no-module': {
+  '14-index-mts-no-tsconfig-node-no-module': {
     handler: ['index.mjs'],
     moduleType: 'esm',
   },

Analysis

The new test fixture 13-index-mts-no-tsconfig-node-no-module uses the same number "13" as the existing 13-app-js-no-module fixture. This creates confusion and potential issues in test organization.

Looking at the test fixture numbering sequence, the next available number should be "14". The directory should be renamed to 14-index-mts-no-tsconfig-node-no-module, and the corresponding test entry in packages/hono/test/unit/build.test.ts should be updated from '13-index-mts-no-tsconfig-node-no-module' to '14-index-mts-no-tsconfig-node-no-module'.

This also affects the package-lock.json file in the fixture directory, which contains the directory name in its "name" field and should be updated accordingly.

packages/node/src/typescript.ts

packages/express/test/unit/build.test.ts

packages/hono/test/unit/build.test.ts

…ith-no-tsconfig-are-always-3

This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## vercel@47.0.1 ### Patch Changes - Updated dependencies \[[`17f3c91aa96ce272d265d809f3b765a12a1f38b3`](17f3c91), [`fea94eea32f9df7c72d9ea95434d84c44f4ef082`](fea94ee)]: - @vercel/next@4.12.4 - @vercel/hono@0.0.20 - @vercel/node@5.3.19 - @vercel/express@0.0.12 ## @vercel/express@0.0.12 ### Patch Changes - Updated dependencies \[[`fea94eea32f9df7c72d9ea95434d84c44f4ef082`](fea94ee)]: - @vercel/node@5.3.19 ## @vercel/hono@0.0.20 ### Patch Changes - Always compile `.mts` to ESM ([#13693](#13693)) - Updated dependencies \[[`fea94eea32f9df7c72d9ea95434d84c44f4ef082`](fea94ee)]: - @vercel/node@5.3.19 ## @vercel/next@4.12.4 ### Patch Changes - Skip adding rewrite headers when the destination has no rewritten pathname or query (and when external origin is not allowed). This prevents generating an empty `rewrite.headers` object that fails schema validation and restores previous behavior for external or no-op rewrites. ([#13844](#13844)) ## @vercel/node@5.3.19 ### Patch Changes - Always compile `.mts` to ESM ([#13693](#13693)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## vercel@47.0.1 ### Patch Changes - Updated dependencies \[[`17f3c91aa96ce272d265d809f3b765a12a1f38b3`](vercel@17f3c91), [`fea94eea32f9df7c72d9ea95434d84c44f4ef082`](vercel@fea94ee)]: - @vercel/next@4.12.4 - @vercel/hono@0.0.20 - @vercel/node@5.3.19 - @vercel/express@0.0.12 ## @vercel/express@0.0.12 ### Patch Changes - Updated dependencies \[[`fea94eea32f9df7c72d9ea95434d84c44f4ef082`](vercel@fea94ee)]: - @vercel/node@5.3.19 ## @vercel/hono@0.0.20 ### Patch Changes - Always compile `.mts` to ESM ([vercel#13693](vercel#13693)) - Updated dependencies \[[`fea94eea32f9df7c72d9ea95434d84c44f4ef082`](vercel@fea94ee)]: - @vercel/node@5.3.19 ## @vercel/next@4.12.4 ### Patch Changes - Skip adding rewrite headers when the destination has no rewritten pathname or query (and when external origin is not allowed). This prevents generating an empty `rewrite.headers` object that fails schema validation and restores previous behavior for external or no-op rewrites. ([vercel#13844](vercel#13844)) ## @vercel/node@5.3.19 ### Patch Changes - Always compile `.mts` to ESM ([vercel#13693](vercel#13693)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Add .circleci/config.yml * Version Packages (vercel#13862) This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## vercel@47.0.1 ### Patch Changes - Updated dependencies \[[`17f3c91aa96ce272d265d809f3b765a12a1f38b3`](vercel@17f3c91), [`fea94eea32f9df7c72d9ea95434d84c44f4ef082`](vercel@fea94ee)]: - @vercel/next@4.12.4 - @vercel/hono@0.0.20 - @vercel/node@5.3.19 - @vercel/express@0.0.12 ## @vercel/express@0.0.12 ### Patch Changes - Updated dependencies \[[`fea94eea32f9df7c72d9ea95434d84c44f4ef082`](vercel@fea94ee)]: - @vercel/node@5.3.19 ## @vercel/hono@0.0.20 ### Patch Changes - Always compile `.mts` to ESM ([vercel#13693](vercel#13693)) - Updated dependencies \[[`fea94eea32f9df7c72d9ea95434d84c44f4ef082`](vercel@fea94ee)]: - @vercel/node@5.3.19 ## @vercel/next@4.12.4 ### Patch Changes - Skip adding rewrite headers when the destination has no rewritten pathname or query (and when external origin is not allowed). This prevents generating an empty `rewrite.headers` object that fails schema validation and restores previous behavior for external or no-op rewrites. ([vercel#13844](vercel#13844)) ## @vercel/node@5.3.19 ### Patch Changes - Always compile `.mts` to ESM ([vercel#13693](vercel#13693)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> --------- Co-authored-by: Vercel Release Bot <88769842+vercel-release-bot@users.noreply.github.com> Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

jeffsee55 added 2 commits August 7, 2025 15:22

Compile to esm when .mts file is provided as the entrypoint even if…

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node-builder: Always compile `.mts` to ESM #13693

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node-builder: Always compile `.mts` to ESM #13693

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