feat: Add support for TS config files #18134

aryaemami59 · 2024-02-21T16:50:08Z

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This PR:

Adds support for TypeScript config files (eslint.config.ts, eslint.config.mts, eslint.config.cts)
Adds jiti as a dependency.
Conditionally imports jiti based on whether the config file's extension ends with ts.

I went through a lot of different possible ways of implementing it, and this by far seems to be the simplest way of doing it without changing too much of the internals of the package or adding too many dependencies.

Is there anything you'd like reviewers to focus on?

eslint-github-bot · 2024-02-21T16:50:13Z

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eslint-github-bot · 2024-02-21T16:50:53Z

Hi @aryaemami59!, thanks for the Pull Request

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lib/eslint/eslint.js

…onfig.ts

lib/eslint/eslint.js

…onfig.ts

cany748 · 2024-02-29T11:26:14Z

Wouldn't it be better to use Jiti for this? I think it's perfect for this, it's used in Nuxt and TailwindCSS to load configuration from Typescript files. It is much smaller and faster than Typescript.

…onfig.ts

aladdin-add · 2024-03-04T10:04:06Z

the first-class ts config support has been discussed in #12078 eslint/rfcs#50, and seems we didn't come to an agreement to accept it.

aladdin-add · 2024-03-04T10:48:35Z

it should be possible to use ts config in the current config. The easiest way I can think of is to use --config and --loader, something like:

NODE_OPTIONS=--loader=tsx eslint --config=eslint.config.ts xxx

…onfig.ts

aryaemami59 · 2024-03-06T04:31:30Z

@cany748 I had to research it to make sure it doesn't create import side effects. But it seems like you were right, it does what I wanted tsx to do without creating side effects.

aryaemami59 · 2024-03-06T04:43:02Z

@aladdin-add

it should be possible to use ts config in the current config. The easiest way I can think of is to use --config and --loader, something like:
NODE_OPTIONS=--loader=tsx eslint --config=eslint.config.ts xxx

That doesn't work you'll get:

Error: tsx must be loaded with --import instead of --loader

And if you use

NODE_OPTIONS=--import=tsx eslint --config=eslint.config.ts

you'll get a YAMLException error if you have a type annotation anywhere in the config file. And if you don't have a type annotation anywhere you'll still get this error:

Error: ESLint configuration in --config is invalid:
        - Property "" is the wrong type

aladdin-add · 2024-03-06T05:36:36Z

I mean flat config (which is the default in eslint v9). If you are using eslint v8, the default is eslintrc, and you need to specify ESLINT_USE_FLAT_CONFIG=true

aryaemami59 · 2024-03-06T05:50:56Z

@aladdin-add

I mean flat config (which is the default in eslint v9). If you are using eslint v8, the default is eslintrc, and you need to specify ESLINT_USE_FLAT_CONFIG=true

That still won't work with .mts or .cts extensions, it also doesn't respect the type field in package.json.

Out of curiosity what is your opinion in the current solution this PR provides?

…onfig.ts

fasttime · 2024-05-27T12:06:42Z

Thanks for working on this, @aryaemami59! In order to move forward with this pull request, we will need some unit tests to verify that TypeScript config files are being loaded as expected.

My suggestion would be to start looking at these tests and add similar tests to check the behavior with packages that have config files with .ts, .cts and .mts extension in place of .js, .cjs and .mjs respectively. It would be also useful to have a test that checks loading a config file whose path is specified in overrideConfigFile like this one. When you are done, just mark the PR as ready for review. Feel free to ping me if you need any help.

lib/eslint/eslint.js

…onfig.ts

aryaemami59 · 2024-05-29T12:08:32Z

@fasttime

Thanks for working on this, @aryaemami59! In order to move forward with this pull request, we will need some unit tests to verify that TypeScript config files are being loaded as expected.

My suggestion would be to start looking at these tests and add similar tests to check the behavior with packages that have config files with .ts, .cts and .mts extension in place of .js, .cjs and .mjs respectively. It would be also useful to have a test that checks loading a config file whose path is specified in overrideConfigFile like this one. When you are done, just mark the PR as ready for review. Feel free to ping me if you need any help.

Thank you so much, I appreciate it, this was the reason why I haven't written any tests yet, thankfully the problem is resolved thanks to @antfu. I will start writing a bunch of tests now!

Co-authored-by: Anthony Fu <anthonyfu117@hotmail.com>

- This is not only done to reduce some potential redundancy down the line, but to ensure that TS config files are able to handle `type` imports as that is something most people are likely going to do.

…onfig.ts

; branch 'main' of https://github.com/eslint/eslint into eslint.config.ts

Note: `isRunningInBun` and `isRunningInDeno` are functions to make treeshaking for consuming libraries easier.

- This is done for mainly 2 reasons: 1. We don't know how many runtime environments are going to support loading TS files natively in the future, so this saves us having to check for every single one. 2. This also ensures that we give the user the option of passing their own TS loader of choice through `NODE_OPTIONS` in CLI for example: `NODE_OPTIONS=--import=tsx/esm`, without ESLint getting in the way and potentially causing conflicts between multiple loaders.

…onfig.ts

aryaemami59 · 2024-05-31T14:22:01Z

Not sure which approach is the way to go atm, I would love some feedback on this, i'm a little torn between the first and second approach, though I'm kind of leaning towards the second one.

fasttime · 2024-05-31T17:51:06Z

Not sure which approach is the way to go atm, I would love some feedback on this, i'm a little torn between the first and second approach, though I'm kind of leaning towards the second one.

I believe the first approach is more predictable. In the second case, loadTSFile() could fail for any reason (e.g. a runtime error), and it's not trivial to determine if the error occurred because the environment doesn't load TypeScript files natively, or else.

nzakas · 2024-05-31T20:27:16Z

@aryaemami59 @antfu you're both working on PRs for this feature. It would be helpful if you could collaborate to see which approach would be best.

aryaemami59 · 2024-05-31T20:31:02Z

@nzakas I'd love nothing more

aryaemami59 added 2 commits February 20, 2024 03:21

Initial working implementation of TS config files

eac9360

Simplify implementation

3833b5b

github-actions bot added cli Relates to ESLint's command-line interface core Relates to ESLint's core APIs and features labels Feb 21, 2024

aryaemami59 changed the title ~~Add support for TypeScript config files (eslint.config.ts, eslint.config.mts, eslint.config.cts)~~ feat: Add support for TypeScript config files (eslint.config.ts, eslint.config.mts, eslint.config.cts) Feb 21, 2024

aryaemami59 changed the title ~~feat: Add support for TypeScript config files (eslint.config.ts, eslint.config.mts, eslint.config.cts)~~ feat: Add support for TS config files Feb 21, 2024

eslint-github-bot bot added the feature This change adds a new feature to ESLint label Feb 21, 2024

mdjermanovic reviewed Feb 22, 2024

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mdjermanovic reviewed Feb 22, 2024

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aryaemami59 added 3 commits February 23, 2024 13:42

Merge branch 'main' of https://github.com/eslint/eslint into eslint.c…

840378c

…onfig.ts

Merge branch 'main' of https://github.com/eslint/eslint into eslint.c…

150d567

…onfig.ts

Use typescript's transpile() instead of tsx to avoid side effects

f196b6b

aryaemami59 commented Feb 27, 2024

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aryaemami59 added 2 commits February 27, 2024 18:59

Merge branch 'main' of https://github.com/eslint/eslint into eslint.c…

9b630ea

…onfig.ts

Merge branch 'main' of https://github.com/eslint/eslint into eslint.c…

ac08d46

…onfig.ts

Merge branch 'main' of https://github.com/eslint/eslint into eslint.c…

c5a8862

…onfig.ts

aryaemami59 added 3 commits March 5, 2024 13:48

Merge branch 'main' of https://github.com/eslint/eslint into eslint.c…

a016dff

…onfig.ts

Remove unnecessary nullish coalescing

00af268

Use jiti instead of TypeScript

5ee0c4c

aryaemami59 added 7 commits May 11, 2024 03:23

Merge branch 'main' of https://github.com/eslint/eslint into eslint.c…

9f09770

…onfig.ts

Merge branch 'main' of https://github.com/eslint/eslint into eslint.c…

360cf38

…onfig.ts

Make jiti an optional peer dependency

b162744

Throw an error if jiti is not installed

8aca3eb

Add jiti to ignoreDependencies in knip.jsonc

b532667

Merge branch 'main' of https://github.com/eslint/eslint into eslint.c…

9248177

…onfig.ts

Merge branch 'main' of https://github.com/eslint/eslint into eslint.c…

eee920e

…onfig.ts

fasttime added accepted There is consensus among the team that this change meets the criteria for inclusion and removed needs design Important details about this change need to be discussed labels May 27, 2024

fasttime reviewed May 27, 2024

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Merge branch 'main' of https://github.com/eslint/eslint into eslint.c…

5ac3927

…onfig.ts

aryaemami59 and others added 6 commits May 29, 2024 07:18

Fix broken unit tests caused by stubbed process.version

f339591

Co-authored-by: Anthony Fu <anthonyfu117@hotmail.com>

Prioritize JavaScript config files over TypeScript config files

8fa2ddb

Add some basic tests for loading TS config files

822baf7

Fix minor type issues in JSDocs

33f5ee6

Partially Inline the FlatConfig type from @types/eslint to reuse

90657fa

- This is not only done to reduce some potential redundancy down the line, but to ensure that TS config files are able to handle `type` imports as that is something most people are likely going to do.

Merge branch 'main' of https://github.com/eslint/eslint into eslint.c…

9da10d4

…onfig.ts

AriPerkkio mentioned this pull request May 30, 2024

feat!: support eslint@9 and flat config AriPerkkio/eslint-remote-tester#519

Open

aryaemami59 added 5 commits May 30, 2024 16:39

Merge branch 'eslint.config.ts' of https://github.com/aryaemami59/eslint

4467fb3

; branch 'main' of https://github.com/eslint/eslint into eslint.config.ts

Stringify mtime

76c3d28

Check if ESLint is running in Deno or Bun

b0e5f96

Note: `isRunningInBun` and `isRunningInDeno` are functions to make treeshaking for consuming libraries easier.

Merge branch 'main' of https://github.com/eslint/eslint into eslint.c…

ce4b72b

…onfig.ts

Add tests for lintFiles with TS config files

61abc9b

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feat: Add support for TS config files #18134

feat: Add support for TS config files #18134

aryaemami59 commented Feb 21, 2024 •

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aryaemami59 commented May 31, 2024

feat: Add support for TS config files #18134

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feat: Add support for TS config files #18134

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aryaemami59 commented Feb 21, 2024 • edited

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