feat: introduce `tsdown`, support mixed js & ts in codebase #2916

9romise · 2025-08-22T01:58:37Z

Hi 👋, Vue team!

I've been trying to contribute to eslint-plugin-vue and recently noticed there might be plans to rewrite it in TypeScript, though things seem to have stalled. I’d like to help move this effort forward.

This PR introduces tsdown, a tool that can gradually transform mixed JavaScript/TypeScript codebases into pure JavaScript output. This allows us to incrementally migrate the entire project to TypeScript. I’ve already successfully rewritten several files — it works well.

Going forward, I can split the changes into multiple PRs to make review easier.

If there’s anything you’d like me to adjust in this PR, or if you have any feedback, I’d really appreciate your thoughts! 💚

Related: #2777

changeset-bot · 2025-08-22T01:58:40Z

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FloEdelmann

Really nice, thank you!

lib/processor.ts

tsdown.config.ts

2nofa11

If pull request #2931 is merged and incorporated into this PR, it may resolve some of the CI failures!!!

I believe this PR is an excellent fix 😍

package.json

# Conflicts: # eslint.config.mjs # package.json

# Conflicts: # lib/plugin.js # tests/lib/rules/block-order.ts # tools/update-lib-plugin.js

package.json

lib/index.ts

FloEdelmann

Let's go then 🚀 🙂

ota-meshi

LGTM! Thank you so much!

Copilot

Pull request overview

This PR introduces tsdown as a build tool to enable gradual migration from JavaScript to TypeScript in the eslint-plugin-vue codebase. It converts several core files to TypeScript (lib/index.ts, lib/meta.ts, lib/processor.ts) while maintaining compatibility with the existing JavaScript files.

Key changes:

Adds tsdown build configuration and updates CI workflow with a dedicated build job
Converts core plugin files from CommonJS to TypeScript with ESM syntax
Changes package entry point from lib/index.js to dist/index.js (built output)

Reviewed changes

Copilot reviewed 12 out of 14 changed files in this pull request and generated 12 comments.

Show a summary per file

File	Description
tsdown.config.ts	Configures tsdown build tool with entry point, output format (CJS), and file copy settings
tsconfig.json	Updates TypeScript compiler options for modern module resolution (bundler) and ESNext target
package.json	Updates main/types entry points to dist directory and adds build script with tsdown
.gitignore	Adds dist directory to ignored files
.github/workflows/CI.yml	Adds build job and artifact caching for all test jobs
lib/index.ts	Converts main entry point from CommonJS to TypeScript with ESM imports
lib/meta.ts	Converts meta module to TypeScript using JSON import assertion
lib/processor.ts	Converts processor from CommonJS/JSDoc to TypeScript with proper type annotations
lib/plugin.js	Updates requires to reference TypeScript files with .default exports
tools/update-lib-plugin.js	Updates generated code to require TypeScript files
tools/generate-typegen.mjs	Updates import to reference TypeScript source file
docs/.vitepress/theme/components/eslint-code-block.vue	Updates import path to reference lib source directory

Comments suppressed due to low confidence (1)

lib/processor.ts:160

The Position type is used in the function signature but is not imported or defined anywhere in this file. This will cause a TypeScript compilation error. The Position type should be imported from ESLint's types (e.g., import type { Linter } from 'eslint' and then use Linter.Position) or defined as an interface in this file.

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Copilot · 2025-12-15T09:27:32Z

tools/update-lib-plugin.js


 const plugin = {
-  meta: require('./meta'),
+  meta: require('./meta.ts').default,


Using require('./meta.ts').default to import a TypeScript file from a CommonJS module is problematic. After tsdown transpiles the code, the file should be ./meta.js in the dist directory, not ./meta.ts. This will cause a runtime error because the .ts file won't exist in the built output. The require path should reference the transpiled .js file.

Copilot · 2025-12-15T09:27:32Z

docs/.vitepress/theme/components/eslint-code-block.vue

    // Load linter.
    const [plugin, { Linter }, vueEslintParser, globals] = await Promise.all([
-      import('../../../..'),
+      import('../../../../lib/index'),


The import path '../../../../lib/index' attempts to import from the source directory, but with the package.json change, the built output is now in the dist directory. This import should be updated to '../../../../dist/index' or '../../../../lib/index.js' (if the intent is to use the transpiled output), or ensure that Vite/VitePress is configured to handle TypeScript imports from lib/ directory.

Suggested change

import('../../../../lib/index'),

import('../../../../dist/index'),

Copilot · 2025-12-15T09:27:33Z

.github/workflows/CI.yml

+      - name: Restore dist cache
+        uses: actions/download-artifact@v6
+        with:
+          name: dist


The download-artifact action is missing the path parameter to specify where the artifact should be extracted. By default, artifacts are downloaded to the current working directory, but it's unclear if that matches the expected dist location. The path parameter should be explicitly set to dist to ensure the artifact is extracted to the correct location.

Copilot · 2025-12-15T09:27:33Z

.github/workflows/CI.yml

+      - name: Restore dist cache
+        uses: actions/download-artifact@v6
+        with:
+          name: dist


The download-artifact action is missing the path parameter to specify where the artifact should be extracted. By default, artifacts are downloaded to the current working directory, but it's unclear if that matches the expected dist location. The path parameter should be explicitly set to dist to ensure the artifact is extracted to the correct location.

Copilot · 2025-12-15T09:27:33Z

lib/plugin.js

+    '.vue': require('./processor.ts').default,
+    vue: require('./processor.ts').default


Using require('./processor.ts').default to import a TypeScript file from a CommonJS module is problematic. After tsdown transpiles the code, the file should be ./processor.js in the dist directory, not ./processor.ts. This will cause a runtime error because the .ts file won't exist in the built output. The require path should reference the transpiled .js file.

Suggested change

'.vue': require('./processor.ts').default,

vue: require('./processor.ts').default

'.vue': require('./processor.js').default,

vue: require('./processor.js').default

Copilot · 2025-12-15T09:27:34Z

tools/generate-typegen.mjs

 import fs from 'node:fs/promises'
 import { pluginsToRulesDTS } from 'eslint-typegen/core'
-import plugin from '../lib/index.js'
+import plugin from '../lib/index.ts'


Importing a TypeScript file (../lib/index.ts) from an ESM module (.mjs) will fail at runtime because Node.js doesn't natively support TypeScript imports without a loader. Since the build script runs typegen before tsdown, this script executes before the TypeScript files are transpiled. Consider using a TypeScript loader, running this script with tsx/ts-node, or restructuring the build process so typegen runs after the build.

Suggested change

import plugin from '../lib/index.ts'

import plugin from '../lib/index.js'

Copilot · 2025-12-15T09:27:34Z

.github/workflows/CI.yml

+      - name: Restore dist cache
+        uses: actions/download-artifact@v6
+        with:
+          name: dist


The download-artifact action is missing the path parameter to specify where the artifact should be extracted. By default, artifacts are downloaded to the current working directory, but it's unclear if that matches the expected dist location. The path parameter should be explicitly set to dist to ensure the artifact is extracted to the correct location.

Copilot · 2025-12-15T09:27:35Z

.github/workflows/CI.yml

+      - name: Restore dist cache
+        uses: actions/download-artifact@v6
+        with:
+          name: dist


The download-artifact action is missing the path parameter to specify where the artifact should be extracted. By default, artifacts are downloaded to the current working directory, but it's unclear if that matches the expected dist location. The path parameter should be explicitly set to dist to ensure the artifact is extracted to the correct location.

Copilot · 2025-12-15T09:27:35Z

.github/workflows/CI.yml

+      - name: Restore dist cache
+        uses: actions/download-artifact@v6
+        with:
+          name: dist


The download-artifact action is missing the path parameter to specify where the artifact should be extracted. By default, artifacts are downloaded to the current working directory, but it's unclear if that matches the expected dist location. The path parameter should be explicitly set to dist to ensure the artifact is extracted to the correct location.

Copilot · 2025-12-15T09:27:35Z

.github/workflows/CI.yml

+          node-version: lts/*
+
+      - name: Install Packages
+        run: npm install


The build job uses npm install without the --legacy-peer-deps flag, while the lint job uses npm install --legacy-peer-deps. This inconsistency could lead to different dependency resolution and potential build failures. The build job should use the same installation command as other jobs for consistency.

Suggested change

run: npm install

run: npm install --legacy-peer-deps

9romise added 5 commits August 21, 2025 17:39

feat: introduce tsdown, support js & ts

b9ad774

fix: dont bundle typescript

928fe26

chore: update

1b24273

chore: update

0f786d8

refactor: rewrite processor in ts

aedcd8d

9romise added 3 commits August 22, 2025 10:01

chore: specific tsdown target

bd930b7

fix: dont touch docs

79d440d

ci: try fix

18d7488

9romise changed the title ~~feat: introduce tsdown, support js & ts~~ feat: introduce tsdown, support mixed js & ts in codebase Aug 22, 2025

9romise marked this pull request as draft August 22, 2025 02:24

9romise added 2 commits August 22, 2025 10:40

fix: correct docs dev & build

861c1d6

chore: update

3d7f91c

9romise marked this pull request as ready for review August 22, 2025 02:47

FloEdelmann reviewed Aug 25, 2025

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chore: update

f1c5923

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9romise marked this pull request as draft August 25, 2025 10:57

This was referenced Sep 6, 2025

Align import integration fixture with supported ESLint versions #2930

Closed

test(integrations/import): align fixture to ESLint ^9 #2931

Merged

2nofa11 reviewed Sep 6, 2025

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9romise added 8 commits October 30, 2025 14:48

build: remove specific node version

eb2d18d

chore: use import instead of require in esm files

27f3479

Merge branch 'master' into rewrite-ts

8c11d97

chore: update tsdown

17974eb

ci: add build in workflow

5e71d49

fix: don't fix extension

6c4041b

chore: update

8d33d93

Merge branch 'master' into pr/2916

f081f42

9romise added 2 commits November 22, 2025 23:08

Merge remote-tracking branch 'upstream/master' into rewrite-ts

7633074

chore: update typegen

75b42d3

9romise mentioned this pull request Nov 22, 2025

refactor: split configs and plugin to separate modules #2967

Merged

9romise added 5 commits November 23, 2025 00:00

cherry-pick: vuejs#2967

34f9c2b

chore: update plugin.js

4f2f525

refactor: rewrite index in .ts

7cfa8d0

cherry-pick: vuejs#2968

e3dbe93

chore: fix lint

b92bc9c

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9romise marked this pull request as ready for review November 22, 2025 16:42

9romise mentioned this pull request Nov 22, 2025

test: rewrite some files in .ts #2968

Merged

9romise added 2 commits November 27, 2025 20:50

Merge branch 'master' into rewrite-ts

46ac044

# Conflicts: # eslint.config.mjs # package.json

chore: use latest tsdown, don't override rolldown

9c58e1f

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9romise added 2 commits December 5, 2025 11:25

Merge branch 'master' into rewrite-ts

e4a6bdb

# Conflicts: # lib/plugin.js # tests/lib/rules/block-order.ts # tools/update-lib-plugin.js

build: upgrade tsdown

7559e8d

9romise marked this pull request as draft December 5, 2025 03:35

fix: includes removed-rules

7e482cb

9romise marked this pull request as ready for review December 5, 2025 03:43

9romise requested a review from FloEdelmann December 5, 2025 03:43

ota-meshi reviewed Dec 5, 2025

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FloEdelmann reviewed Dec 12, 2025

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FloEdelmann mentioned this pull request Dec 12, 2025

refactor: migrate to pnpm workspace #2961

Draft

FloEdelmann approved these changes Dec 15, 2025

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FloEdelmann requested review from Copilot, ota-meshi and waynzh December 15, 2025 09:19

Copilot started reviewing on behalf of FloEdelmann December 15, 2025 09:20 View session

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Copilot AI reviewed Dec 15, 2025

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	import('../../../../lib/index'),
	import('../../../../dist/index'),

		'.vue': require('./processor.ts').default,
		vue: require('./processor.ts').default

	import plugin from '../lib/index.ts'
	import plugin from '../lib/index.js'

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9romise commented Aug 22, 2025

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feat: introduce `tsdown`, support mixed js & ts in codebase #2916

feat: introduce `tsdown`, support mixed js & ts in codebase #2916

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