module: refactor commonjs typescript loader by marco-ippolito · Pull Request #58657 · nodejs/node

marco-ippolito · 2025-06-10T06:22:38Z

As suggested by @joyeecheung nodejs/typescript#37 (comment), we can refactor the commonjs loader so that we dont have to expose in the Module._extensions the TypeScript file extensions.

This also means that require.extensions will be inconsistent but it already is since .cjs and .mjs are not exposed

This should unblock the backport of Type Stripping in Node v22.

I tested it against @hardfist https://github.com/hardfist/webpack-ts-break and it fixes the breaking change:

Node v24
marcoippolito@marcos-MacBook-Pro-3 webpack-ts-break % node node_modules/webpack/bin/webpack.js
[webpack-cli] Failed to load '/Users/marcoippolito/Documents/projects/test/webpack-ts-break/webpack.config.ts' config
[webpack-cli] ReferenceError: __dirname is not defined
at /Users/marcoippolito/Documents/projects/test/webpack-ts-break/webpack.config.ts:5:12
at ModuleJobSync.runSync (node:internal/modules/esm/module_job:455:35)
at ModuleLoader.importSyncForRequire (node:internal/modules/esm/loader:435:47)
at loadESMFromCJS (node:internal/modules/cjs/loader:1565:24)
at Module._compile (node:internal/modules/cjs/loader:1716:5)
at Object.loadTS [as .ts] (node:internal/modules/cjs/loader:1826:10)
at Module.load (node:internal/modules/cjs/loader:1469:32)
at Module._load (node:internal/modules/cjs/loader:1286:12)
at TracingChannel.traceSync (node:diagnostics_channel:322:14)
at wrapModuleLoad (node:internal/modules/cjs/loader:235:24)
This PR
marcoippolito@marcos-MacBook-Pro-3 webpack-ts-break % ../../forks/node/out/Release/node node_modules/webpack/bin/webpack.js
asset main.js 21 bytes [emitted] [minimized] (name: main)
./src/index.js 20 bytes [built] [code generated]
webpack 5.99.9 compiled successfully in 100 ms

This commit refactors the CommonJS loader to remove TypeScript-specific extensions from the require.extensions object for compatibility with libraries that depended on it to initialize extenal TypeScript loaders.

nodejs-github-bot · 2025-06-10T06:22:43Z

Review requested:

@nodejs/loaders

codecov · 2025-06-10T07:16:58Z

Codecov Report

Attention: Patch coverage is 78.94737% with 4 lines in your changes missing coverage. Please review.

Project coverage is 90.15%. Comparing base (a45f1ad) to head (c942d9f).
Report is 142 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/internal/modules/cjs/loader.js	78.94%	4 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #58657 +/- ##
=======================================
Coverage 90.14% 90.15% =======================================
Files 636 636 Lines 188030 187953 -77 Branches 36894 36882 -12 =======================================
- Hits 169506 169451 -55 + Misses 11276 11268 -8 + Partials 7248 7234 -14

Files with missing lines	Coverage Δ
lib/internal/modules/cjs/loader.js	`97.85% <78.94%> (+0.06%)`	⬆️

... and 25 files with indirect coverage changes

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mcollina

lgtm

nodejs-github-bot · 2025-06-10T08:58:47Z

CI: https://ci.nodejs.org/job/node-test-pull-request/67374/

nodejs-github-bot · 2025-06-10T09:46:26Z

CI: https://ci.nodejs.org/job/node-test-pull-request/67375/

Co-authored-by: Joyee Cheung <joyeec9h3@gmail.com>

nodejs-github-bot · 2025-06-10T12:15:53Z

CI: https://ci.nodejs.org/job/node-test-pull-request/67378/

hardfist · 2025-06-11T01:37:06Z

@marco-ippolito great job! may I ask whether this compatible fix be backported to Node.js 23&24? we're willing to migrate to native typescript support but a easier progressive migration is always preferred.

marco-ippolito · 2025-06-11T02:33:54Z

v24 yes in the next release
v23 no since is eol

nodejs-github-bot · 2025-06-12T06:35:23Z

Landed in 708477b

This commit refactors the CommonJS loader to remove TypeScript-specific extensions from the require.extensions object for compatibility with libraries that depended on it to initialize extenal TypeScript loaders. PR-URL: #58657 Refs: nodejs/typescript#37 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Pietro Marchini <pietro.marchini94@gmail.com> Reviewed-By: Xuguang Mei <meixuguang@gmail.com>

JLHwung · 2025-06-23T12:48:38Z

With this change, how should a library detect if the current node has enabled builtin strip-types support? Should a library do the version check?

Previously in Babel we checked require.extensions (set by ts-node, tsx or node < 24.3) and nudged users to upgrade Node or install the aforementioned libraries if they want to use a TS Babel config file such as babel.config.cts.

marco-ippolito · 2025-06-23T12:55:16Z

With this change, how should a library detect if the current node has enabled builtin strip-types support? Should a library do the version check?
Previously in Babel we checked require.extensions (set by ts-node, tsx or node < 24.3) and nudged users to upgrade Node or install the aforementioned libraries if they want to use a TS Babel config file such as babel.config.cts.

process.features.typescript
https://nodejs.org/api/process.html#processfeaturestypescript

This commit refactors the CommonJS loader to remove TypeScript-specific extensions from the require.extensions object for compatibility with libraries that depended on it to initialize extenal TypeScript loaders. PR-URL: nodejs#58657 Refs: nodejs/typescript#37 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Pietro Marchini <pietro.marchini94@gmail.com> Reviewed-By: Xuguang Mei <meixuguang@gmail.com>

This commit refactors the CommonJS loader to remove TypeScript-specific extensions from the require.extensions object for compatibility with libraries that depended on it to initialize extenal TypeScript loaders. PR-URL: #58657 Backport-PR-URL: #57298 Refs: nodejs/typescript#37 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com> Reviewed-By: Pietro Marchini <pietro.marchini94@gmail.com> Reviewed-By: Xuguang Mei <meixuguang@gmail.com> PR-URL: #56350Fixes: nodejs/typescript#17

module: refactor commonjs typescript loader
12132fa
This commit refactors the CommonJS loader to remove TypeScript-specific extensions from the require.extensions object for compatibility with libraries that depended on it to initialize extenal TypeScript loaders.

nodejs-github-bot added module Issues and PRs related to the module subsystem. needs-ci PRs that need a full CI run. labels Jun 10, 2025

marco-ippolito added the strip-types Issues or PRs related to strip-types support label Jun 10, 2025

marco-ippolito mentioned this pull request Jun 10, 2025
Unflagging Type Stripping in Node.js v22 nodejs/typescript#37
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Comment threadlib/internal/modules/cjs/loader.js Outdated

fix: linting
c942d9f
Co-authored-by: Joyee Cheung <joyeec9h3@gmail.com>

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nodejs-github-bot merged commit 708477b into nodejs:mainJun 12, 2025

github-actionsBot mentioned this pull request Jun 16, 2025
2025-06-17, Version 24.3.0 (Current) #58727
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nicolo-ribaudo mentioned this pull request Jun 22, 2025
Improve TS babel config loading babel/babel#17392
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github-actionsBot mentioned this pull request Jun 23, 2025
2025-06-24, Version 24.3.0 (Current) #58804
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This was referenced Jun 24, 2025
[BUG] Don't rely on require.extentions node-config/node-config#787
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webpack.config.ts is not compatible with Node.js v24 webpack/webpack.js.org#7629
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github-actionsBot mentioned this pull request Jun 24, 2025
2025-06-24, Version 24.3.0 (Current) #58813
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marco-ippolito added backport-open-v22.x Indicate that the PR has an open backport dont-land-on-v20.x labels Jun 25, 2025

marco-ippolito added backported-to-v22.x PRs backported to the v22.x-staging branch. and removed backport-open-v22.x Indicate that the PR has an open backport labels Jul 4, 2025

This was referenced Aug 5, 2025
Regression: require() with runtime loaders crashes in v22.18.0 – TypeError undefined.getStatus() in getModuleJobForRequire #59366
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node 22.18 breaks npm package because of experimental-strip-types enabled #59364
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