fix(core): FileLoader support .mjs as first-class by elrrrrrrr · Pull Request #6023 · eggjs/egg

elrrrrrrr · 2026-07-06T02:48:06Z

What

Add .mjs to FileLoader's default match glob so .mjs files are scanned the same as .js/.ts.

- return isSupportTypeScript() ? ['**/*.(js|ts)', '!**/*.d.ts'] : ['**/*.js'];
+ return isSupportTypeScript() ? ['**/*.(js|ts|mjs)', '!**/*.d.ts'] : ['**/*.{js,mjs}'];

Why

The default match only includes .js/.ts, so .mjs files are silently skipped. egg4 plugins built as ESM (e.g. tsdown/tsc emitting .mjs) put their app/middleware, app/extend, config etc. in .mjs. Those never get loaded → app.middlewares is missing the plugin's middleware, and a lookup like app.middlewares[name] throws Middleware xxx not found.

Concretely, an ESM plugin shipping app/middleware/xxx.mjs and pushing xxx into config.tr.middleware (or coreMiddleware) currently fails to boot because the middleware file is never scanned.

In type: module packages .js is already ESM, but many build toolchains emit .mjs explicitly. Treating .mjs as first-class avoids forcing every ESM plugin to re-emit as .js.

Status

Draft — opening for discussion / direction. Happy to add tests + cover the .mjs load path if this direction looks right.

Summary by CodeRabbit

New Features
- Expanded file loading support to include .mjs and .cjs files in addition to .js, with TypeScript projects also recognizing .ts sources.
- When both source and compiled versions exist, the TypeScript file now takes precedence.
Bug Fixes
- Prevented compiled .js, .mjs, and .cjs files from being loaded alongside matching TypeScript files, avoiding duplicate attachments.

The default FileLoader match glob only includes `.js`/`.ts` (and `.js` when TypeScript is off), so `.mjs` files are silently skipped. egg4 plugins built as ESM (e.g. via tsdown/tsc emitting `.mjs`) put their `app/middleware`, `app/extend`, `config` etc. in `.mjs`, which then never get loaded — e.g. `app.middlewares` ends up missing plugin middleware, and any lookup like `app.middlewares[name]` throws "Middleware xxx not found". Add `.mjs` to the default match so ESM plugins shipping `.mjs` are scanned the same as `.js`. In `type: module` packages `.js` is already ESM, but many build toolchains emit `.mjs` explicitly; treating `.mjs` as first-class avoids requiring every ESM plugin to re-emit as `.js`.

coderabbitai · 2026-07-06T02:48:19Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: f3b4c420-ea80-4171-af52-517b6c8d92a1

📥 Commits

Reviewing files that changed from the base of the PR and between d55efa3 and 2452d45.

📒 Files selected for processing (8)

packages/core/src/loader/file_loader.ts
packages/core/test/egg-ts.test.ts
packages/core/test/fixtures/egg-ts-js/app/service/dual.mjs
packages/core/test/fixtures/egg-ts-js/app/service/dual.ts
packages/core/test/fixtures/egg-ts-js/app/service/dualc.cjs
packages/core/test/fixtures/egg-ts-js/app/service/dualc.ts
packages/core/test/fixtures/egg-ts-js/app/service/pureCjs.cjs
packages/core/test/fixtures/egg-ts-js/app/service/pureMjs.mjs

📝 Walkthrough

Walkthrough

The change extends FileLoader to match and load .mjs/.cjs files alongside .js/.ts, and expands the ignore logic to skip compiled .js/.mjs/.cjs files when a corresponding .ts source exists. New fixture files and a test case validate discovery and precedence behavior.

Changes

mjs/cjs loading support

Layer / File(s)	Summary
File loader glob matching and ignore logic `packages/core/src/loader/file_loader.ts`	Default glob patterns now include `mjs`/`cjs` in both TypeScript-enabled and disabled modes; ignore logic extended to skip `.js`, `.mjs`, and `.cjs` compiled files when a matching `.ts` sibling exists.
Fixtures and test verifying precedence `packages/core/test/egg-ts.test.ts`, `packages/core/test/fixtures/egg-ts-js/app/service/{pureMjs.mjs,pureCjs.cjs,dual.ts,dual.mjs,dualc.ts,dualc.cjs}`	New fixture services define `loadedFrom` markers for `mjs`/`cjs`/`ts` sources; a new test verifies standalone `.mjs`/`.cjs` loading and confirms `.ts` sources take precedence over compiled siblings.

Estimated code review effort: 2 (Simple) | ~10 minutes

Sequence Diagram(s)

Not applicable — the changes are focused loader logic and fixture/test additions without multi-component orchestration warranting a sequence diagram.

Suggested reviewers: fengmk2, killagu

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title correctly captures the main change: FileLoader now treats .mjs as a first-class match.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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gemini-code-assist

Code Review

This pull request updates the default file loader match pattern to include .mjs files alongside .js and .ts files. The reviewer identified a potential issue where adding .mjs support could lead to duplicate loading of both .ts and compiled .mjs files, as the existing deduplication logic only checks for .js files. It is recommended to update the deduplication check to also handle .mjs files to prevent application crashes.

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codecov · 2026-07-06T02:49:37Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.97%. Comparing base (d55efa3) to head (2452d45).

Additional details and impacted files

@@           Coverage Diff           @@
##             next    #6023   +/-   ##
=======================================
  Coverage   81.96%   81.97%           
=======================================
  Files         678      678           
  Lines       20800    20800           
  Branches     4147     4147           
=======================================
+ Hits        17048    17050    +2     
+ Misses       3235     3233    -2     
  Partials      517      517

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@gemini-code-assist

…s/.cjs - Add `.cjs` to the default FileLoader match alongside `.mjs`. - Extend the source-wins de-dup (previously `.js`-only) to `.mjs`/`.cjs`: when a `.ts` source and its compiled `.js`/`.mjs`/`.cjs` sibling coexist in the same directory (e.g. tsc/tsdown output kept beside the source during development), the `.ts` source wins and the compiled sibling is ignored — otherwise both are attached to the same property and `can't overwrite property` is thrown. (per @gemini-code-assist review) Priority when several extensions coexist for one basename: `.ts` (source) > compiled `.js`/`.mjs`/`.cjs`. Adds fixtures + a test covering standalone .mjs/.cjs loading and the .ts-over-.mjs / .ts-over-.cjs de-dup.

elrrrrrrr · 2026-07-06T03:10:37Z

Thanks @gemini-code-assist — good catch, fixed in 4a2c566.

Extended the "source wins" de-dup (previously .js-only) to .mjs/.cjs, so a compiled sibling is ignored while the .ts source exists:

if (filepath.endsWith('.js') || filepath.endsWith('.mjs') || filepath.endsWith('.cjs')) {
  const filepathTs = filepath.replace(/\.(?:js|mjs|cjs)$/, '.ts');
  if (filepaths.includes(filepathTs)) continue;
}

Priority when several extensions coexist for one basename: .ts (source) > compiled .js/.mjs/.cjs. Coexistence among the compiled formats themselves (e.g. foo.js + foo.mjs with no .ts) is a build misconfiguration and still surfaces the existing can't overwrite property error deliberately.

Also added .cjs to the default match (alongside .mjs) and a test in egg-ts.test.ts covering standalone .mjs/.cjs loading plus the .ts-over-.mjs / .ts-over-.cjs de-dup.

gemini-code-assist · 2026-07-06T03:10:50Z

Thanks for the update, @elrrrrrrr. The logic for handling the source file priority and the addition of .cjs support looks solid and addresses the potential for duplicate loading when compiled files coexist with their .ts sources. The added tests in egg-ts.test.ts provide good coverage for these scenarios. This looks like a complete and well-thought-out solution.

killagu

LGTM

Copilot

Pull request overview

This PR updates Egg core’s FileLoader default glob matching so that .mjs files (and, in the current implementation, .cjs as well) are treated as first-class load targets alongside .js/.ts, and adds regression fixtures/tests to ensure .ts sources take precedence over adjacent compiled outputs.

Changes:

Expand FileLoader default match patterns to include .mjs/.cjs, and ignore compiled siblings when a .ts source exists.
Add fixture services for standalone .mjs/.cjs and “dual” .ts + compiled output coexistence.
Add a test asserting .mjs/.cjs loading and .ts-over-compiled precedence.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/core/src/loader/file_loader.ts	Extend default glob match to include `.mjs`/`.cjs` and skip compiled siblings when `.ts` exists.
packages/core/test/egg-ts.test.ts	Add a regression test around `.mjs`/`.cjs` loading and precedence rules.
packages/core/test/fixtures/egg-ts-js/app/service/pureMjs.mjs	New standalone `.mjs` service fixture.
packages/core/test/fixtures/egg-ts-js/app/service/pureCjs.cjs	New standalone `.cjs` service fixture.
packages/core/test/fixtures/egg-ts-js/app/service/dual.ts	New `.ts` source fixture intended to win over compiled sibling.
packages/core/test/fixtures/egg-ts-js/app/service/dual.mjs	New compiled `.mjs` sibling fixture intended to be ignored when `.ts` exists.
packages/core/test/fixtures/egg-ts-js/app/service/dualc.ts	New `.ts` source fixture intended to win over compiled sibling.
packages/core/test/fixtures/egg-ts-js/app/service/dualc.cjs	New compiled `.cjs` sibling fixture intended to be ignored when `.ts` exists.

 function getDefaultFileLoaderMatch(): string[] {
-  return isSupportTypeScript() ? ['**/*.(js|ts)', '!**/*.d.ts'] : ['**/*.js'];
+  return isSupportTypeScript() ? ['**/*.(js|ts|mjs|cjs)', '!**/*.d.ts'] : ['**/*.{js,mjs,cjs}'];
 }


+  it('should load mjs/cjs and prefer the ts source over its compiled mjs/cjs', async () => {
+    mm(process.env, 'EGG_TYPESCRIPT', 'true');
+    app = createApp('egg-ts-js');
+
+    // loadService must not throw "can't overwrite property" even though
+    // `dual.ts`+`dual.mjs` and `dualc.ts`+`dualc.cjs` coexist in the directory.
+    await app.loader.loadService();
+
+    // standalone `.mjs` / `.cjs` are scanned and loaded as first-class files
+    assert(app.serviceClasses.pureMjs);
+    assert.equal(app.serviceClasses.pureMjs.loadedFrom, 'mjs');
+    assert(app.serviceClasses.pureCjs);
+    assert.equal(app.serviceClasses.pureCjs.loadedFrom, 'cjs');
+
+    // priority: when a `.ts` source and its compiled `.mjs`/`.cjs` coexist,
+    // the `.ts` source wins and the compiled sibling is ignored.
+    assert(app.serviceClasses.dual);
+    assert.equal(app.serviceClasses.dual.loadedFrom, 'ts');
+    assert(app.serviceClasses.dualc);
+    assert.equal(app.serviceClasses.dualc.loadedFrom, 'ts');
+  });


fengmk2 · 2026-07-07T15:00:44Z

@codex review

chatgpt-codex-connector · 2026-07-07T15:06:17Z

Codex Review: Didn't find any major issues. Can't wait for the next one!

Reviewed commit: 2452d45428

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gemini-code-assist Bot reviewed Jul 6, 2026

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Comment thread packages/core/src/loader/file_loader.ts Outdated

Merge branch 'next' into fix/file-loader-support-mjs

2452d45

elrrrrrrr requested review from fengmk2 and killagu July 7, 2026 08:55

elrrrrrrr marked this pull request as ready for review July 7, 2026 08:55

Copilot AI review requested due to automatic review settings July 7, 2026 08:55

Copilot started reviewing on behalf of elrrrrrrr July 7, 2026 08:55 View session

killagu approved these changes Jul 7, 2026

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Copilot AI reviewed Jul 7, 2026

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fengmk2 approved these changes Jul 7, 2026

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fengmk2 merged commit a71ef2b into eggjs:next Jul 7, 2026
22 checks passed

elrrrrrrr mentioned this pull request Jul 9, 2026

fix(tegg-loader): include mjs and cjs extensions #6026

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fix(core): FileLoader support .mjs as first-class#6023

fix(core): FileLoader support .mjs as first-class#6023
fengmk2 merged 3 commits into
eggjs:nextfrom
elrrrrrrr:fix/file-loader-support-mjs

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