Add `files: []` to the configuration object

[sindresorhus]

What is the problem you're trying to solve?

In my projects, I prefer to always glob for all CSS files **/*.css and rather ignore the few CSS files I want instead of explicitly specify every file. When having to specify the files, it's easy to forget some files, especially when they're added later.

What solution would you like to see?

I would like to see a top-level setting called files that accepts an array of strings. I could then set files: ['**/*.css'], in my shareable config and use the ignoreFiles in my projects to ignore project-specific files.

---

There are other benefits to specifying the files in a config object:

• The run script becomes less messy. Before: {"lint": "xo && stylelint foo.js bar.js 'fixtures/*.css'"} After: {"lint": "xo && stylelint"}
• People often forget to quote the globs, which can lead to weird inconsistencies, since if you don't quote them, they're interpreted as shell globs instead of being passed in as strings to stylelint and its glob handling. By specifying the files in the stylelint config, that's not a problem.
• Editor plugins can read the files config and know which files to lint. It cannot reliably parse the run script commands.

I have had files config in both the AVA and XO projects for years with great success.

---

This is a duplicate of #2580, but I chose to open a new issue as I feel I have a different use-case and many more arguments for why it makes sense.

[alexander-akait]

Sounds reasonable, strange what eslint doesn't support this (and other feature like #3858 and #3859) :confused:

[jeddy3]

Thanks for listing out the benefits and noting a similar approach in AVA and XO.

This sounds like a good idea. It's related to https://github.com/stylelint/stylelint/issues/3411, which is also about improving the experience of using stylelint.

[Mouvedia]

1. should files support negation? (dupe of existing ignorefiles)
   • if it's supported does the cli input get the priority? which list overwrite or merge onto the other? e.g. "!foo.css" from the cli "foo.css" in files should ignorefiles be deprecated?
2. what's the merger strategy for ignored files/directories?
   • should .stylelintignore + ignorefiles be an union or a concat?
   • take --ignore-path and --ignore-pattern into account before/after the merger
3. mergeConfigs function doesn't have a case for ignorefiles; should it be a set or a add (i.e. reassign or merge) in cases of extends
4. does https://stylelint.io/user-guide/usage/node-api/#files become optional if code or files (from config) is provided?

---

I guess no one has a clue so Ill just use common sense and pick what seems the best if I ever work on this one.

[ybiquitous]

I've reverted the status to needs discussion because I think this feature may conflict with #3411. See also the discussion on #6617.

[ybiquitous]

Also, we need to consider @Mouvedia's questions on https://github.com/stylelint/stylelint/issues/3860#issuecomment-1422373981.

[jeddy3]

Labelling as ready to implement following the discussion in https://github.com/stylelint/stylelint/issues/6689.

Picking up https://github.com/stylelint/stylelint/issues/6689#issuecomment-1469041369

Let's support strings and an array of strings to be consistent with the other options, including all secondary options for rules. In hindsight, accepting strings was probably a mistake, but we have consistently done it for our options. We can consider moving to arrays only in a major release.

[ybiquitous]

I try responding to some questions in https://github.com/stylelint/stylelint/issues/3860#issuecomment-1422373981.

should files support negation? (dupe of existing ignorefiles)

I think it makes sense to allow negation patterns for files because detecting a negation in a glob pattern may be difficult and need extra parsing.

There should be no problems even if people use both negation patterns in files and ignoreFiles at their own risk. Perhaps such use cases are very few.

should ignorefiles be deprecated?

I think we should continue to support ignoreFiles for backward compatibility as long as there are no inconveniences.

[silverwind]

Would a pattern **/*.css include files like node_modules/foo/index.css? If not, by which mechanism is node_modules excluded?

[ybiquitous]

No, the current behavior (ignoring node_modules by default) will be kept:

https://github.com/stylelint/stylelint/blob/b92260f415ae2e1c1ee053ea01658be0b063899b/lib/standalone.mjs#L26

[Mouvedia]

Is this issue ready to be implemented?

[ybiquitous]

If we introduce the flat config (#7408), this issue no longer seems to be needed; otherwise, at least, it seems to need to reconsider an expected behavior.

[jeddy3]

There's quite a bit to consider here. We want to enable {"lint": "xo && stylelint"} while also being compatible with a future flat config. I believe this is possible. With their larger resources, the ESLint team has put a lot of legwork into designing and testing their flat config. We can save time by mimicking their choices.

We can use files: [] as an opt-in for that behaviour, i.e.:

module.exports = {
  "files": ["**/*.css"],
  "rules": { "color-no-named": true }
}

Would:

• disables .stylelintignore and --ignore-pattern
• disables --ignore-path
• files: [] only accept an array
• the Node.js API files: [] and the CLI input glob act as a filter for files: [] in the configuration object

The latter makes the Node.js API files: [] optional.

We may also want to add an ignores: [] configuration property that has a different behaviour to ignoreFiles: [], i.e. it supports unignoring files through negation rather than removing the defaults. If we did, files: [] would also disable ignoreFiles: [].

The behaviour that'd be triggered by files: [] feels more straightforward to reason about compared to our current mishmash of ignoreFiles: [] and .stylelintignore/--ignore-pattern.

We'll need to be clear in our documentation that using files: [] in the configuration object opts into this new behaviour.

Do we think this approach is worth exploring? If so, we'll likely want to put together a PoC PR to assess whether it's possible to have the current and new behaviours work alongside each other and the code complexity of doing so.

[Mouvedia]

We may also want to add an ignores: [] configuration property that has a different behaviour to ignoreFiles: []

Can you separate this into its own issue and punt it to v17?

[jeddy3]

Can you separate this into its own issue

Done in https://github.com/stylelint/stylelint/issues/7449.