# Stylelint

[Stylelint](https://stylelint.io/) is a popular linter for CSS.

## Run Locally

The mozlint integration of Stylelint can be run using mach:

```{eval-rst}
.. parsed-literal::

    $ mach lint --linter stylelint <file paths>
```

Alternatively, omit the `--linter stylelint` and run all configured linters, which will include
Stylelint.

Stylelint also supports the `--fix` option to autofix most errors raised from most of the rules.

See the [Usage guide] for more options.

## Understanding Rules and Errors

- Only some files are linted, see the {searchfox}`configuration <tools/lint/stylelint.yml>` for details.

  - By design we do not lint/format reftests not crashtests as these are specially crafted tests.

- If you don't understand a rule, you can look it in [stylelint.io's rule list] for more
  information about it.

## Enabling new rules and adding plugins

Please see [this page for enabling new rules](stylelint/enabling-rules.html).

## Common Issues and How To Solve Them

### This code should neither be linted nor formatted

- If it is a third-party piece of code, please add it to {searchfox}`ThirdPartyPaths.txt <tools/rewriting/ThirdPartyPaths.txt>`.
- If it is a generated file, please add it to {searchfox}`Generated.txt <tools/rewriting/Generated.txt>`.
- If intentionally invalid, please add it to {searchfox}`.stylelintignore <.stylelintignore>`.

## Configuration

The global configuration file lives in `topsrcdir/.stylelintrc.js`.
For an overview of the supported configuration, see [Stylelint's documentation].

Please keep differences in rules across the tree to a minimum. We want to be consistent to
make it easier for developers.

## Sources

- {searchfox}`Configuration (YAML) <tools/lint/stylelint.yml>`
- {searchfox}`Source <tools/lint/stylelint/__init__.py>`

## Builders

[Gijs Kruitbosch (gijs)](https://people.mozilla.org/s?query=gijs) owns
the builders. Questions can also be asked on #lint:mozilla.org on Matrix.

### Stylelint task

This is a tier-1 task. For test failures the patch causing the
issue should be backed out or the issue fixed.

Some failures can be fixed with `./mach lint -l stylelint --fix path/to/file`.

For test harness issues, file bugs in Developer Infrastructure :: Lint and Formatting.

[stylelint's documentation]: https://stylelint.io/user-guide/configure/
[stylelint.io's rule list]: https://stylelint.io/user-guide/rules/
[usage guide]: ../usage.html