scss-lint is a tool to help keep your SCSS files clean and readable by running it against a collection of configurable linter rules. You can run it manually from the command line, or integrate it into your SCM hooks.

NOTICE: Consider other tools before adopting SCSS-Lint

The Sass core team is now building Sass in Dart instead of Ruby, and will no longer be maintaining the Ruby implementation unless a maintainer steps up to help. Since the SCSS-Lint project relies on the Ruby Sass implementation, this means it will eventually not support the latest Sass features and bug fixes.

One alternative worthy of consideration is stylelint, which supports SCSS natively. If you want to use SCSS-specific rules in addition to stylelint core rules, you need to configure stylelint plugins like stylelint-scss or stylelint-order.

The SCSS-Lint project will continue to accept pull requests and provide basic support on the issue tracker.

Requirements
Installation
Usage
Configuration
Formatters
Exit Status Codes
Linters
Custom Linters
Preprocessing
Automated Code Review
Editor Integration
Git Integration
Rake Integration
Maven Integration
Documentation
Contributing
Community
Changelog
License

Requirements

Ruby 2.4+
Sass 3.5.5+
Files you wish to lint must be written in SCSS (not Sass) syntax

Installation

gem install scss_lint

…or add the following to your Gemfile and run bundle install:

gem 'scss_lint', require: false

The require: false is necessary because scss-lint monkey patches Sass in order to properly traverse the parse tree created by the Sass parser. This can interfere with other applications that invoke the Sass parser after scss-lint libraries have been loaded at runtime, so you should only require it in the context in which you are linting, nowhere else.

Usage

Run scss-lint from the command line by passing in a directory (or multiple directories) to recursively scan:

scss-lint app/assets/stylesheets/

You can also specify a list of files explicitly:

scss-lint app/assets/stylesheets/**/*.css.scss

…or you can lint a file passed via standard input (note the --stdin-file-path flag is required when passing via standard input):

cat some-file | scss-lint --stdin-file-path=path/to/treat/stdin/as/having.scss

scss-lint will output any problems with your SCSS, including the offending filename and line number (if available).

Command Line Flag	Description
`-c`/`--config`	Specify a configuration file to use
`-e`/`--exclude`	Exclude one or more files from being linted
`-f`/`--format`	Output format (see Formatters)
`-o`/`--out`	Write output to a file instead of STDOUT
`-r`/`--require`	Require file/library (mind `$LOAD_PATH`, uses `Kernel.require`)
`-i`/`--include-linter`	Specify which linters you specifically want to run
`-x`/`--exclude-linter`	Specify which linters you don’t want to run
`--stdin-file-path`	When linting a file passed via standard input, treat it as having the specified path to apply the appropriate configuration
`--[no-]color`	Whether to output in color
`-h`/`--help`	Show command line flag documentation
`--show-formatters`	Show all available formatters
`--show-linters`	Show all available linters
`-v`/`--version`	Show version

When running scss-lint with JRuby, using JRuby’s --dev flag will probably improve performance.

Configuration

scss-lint loads configuration in the following order of precedence:

Configuration file specified via the --config flag
Configuration from .scss-lint.yml in the current working directory, if it exists
Configuration from .scss-lint.yml in the user’s home directory, if it exists

All configurations extend the default configuration.

Note: The first configuration file found is the one that is loaded, e.g. the .scss-lint.yml file in the current working directory is loaded instead of the one in the user’s home directory—they are not merged with each other.

Here’s an example configuration file:

scss_files: 'app/assets/stylesheets/**/*.css.scss'

exclude: 'app/assets/stylesheets/plugins/**'

linters:
  BorderZero:
    enabled: false

  Indentation:
    exclude:
      - 'path/to/file.scss'
      - 'path/to/directory/**'
    severity: warning
    width: 2

All linters have an enabled option which can be true or false, which controls whether the linter is run, along with linter-specific options. The defaults are defined in config/default.yml.

Severities

The severity linter option allows you to specify whether the lint should be treated as a warning or an error. Warnings cause scss-lint to exit with a different error code than errors (unless both warnings and errors are present, in which case the error exit code is returned). This is useful when integrating scss-lint with build systems or other executables, as you can rely on its exit status code to indicate whether a lint actually requires attention.

You can also define the default severity for all linters by setting the global severity option.

Excluding Files

The exclude directive allows you to specify a glob pattern of files that should not be linted by scss-lint. Paths are relative to the location of the config file itself if they are not absolute paths. If an inherited file specifies the exclude directive, the two exclusion lists are combined. Any additional exclusions specified via the --exclude flag are also combined. If you need to exclude files for a single linter you can specify the list of files using the linter’s exclude configuration option.

Generating a Configuration

To start using scss-lint you can use the Config Formatter, which will generate an .scss-lint.yml configuration file with all linters which caused a lint disabled. Starting with this as your configuration you can slowly enable each linter and fix any lints one by one.

Disabling Linters via Source

For special cases where a particular lint doesn’t make sense in a specific area of a file, special inline comments can be used to enable/disable linters. Some examples are provided below:

Disable for the entire file

// scss-lint:disable BorderZero
p {
  border: none; // No lint reported
}

Disable a few linters

// scss-lint:disable BorderZero, StringQuotes
p {
  border: none; // No lint reported
  content: "hello"; // No lint reported
}

Disable all lints within a block (and all contained blocks)

p {
  // scss-lint:disable BorderZero
  border: none; // No lint reported
}

a {
  border: none; // Lint reported
}

Disable and enable again

// scss-lint:disable BorderZero
p {
  border: none; // No lint reported
}
// scss-lint:enable BorderZero

a {
  border: none; // Lint reported
}

Disable for just one line

p {
  // No lint reported:
  border: none; // scss-lint:disable BorderZero

  a {
    border: none; // Lint reported
  }
}

Disable/enable all linters

// scss-lint:disable all
p {
  border: none; // No lint reported
}
// scss-lint:enable all

a {
  border: none; // Lint reported
}

Formatters

Default

The default formatter is intended to be easy to consume by both humans and external tools.

scss-lint [scss-files...]

test.scss:2:1 [W] StringQuotes: Prefer single quoted strings
test.scss:2:1 [W] Indentation: Line should be indented 0 spaces, but was indented 1 space
test.scss:5:1 [W] StringQuotes: Prefer single quoted strings
test.scss:6:8 [W] UrlQuotes: URLs should be enclosed in quotes

CleanFiles

Displays a list of all files that were free of lints.

Config

Returns a valid .scss-lint.yml configuration where all linters which caused a lint are disabled. Starting with this as your configuration, you can slowly enable each linter and fix any lints one by one.

scss-lint --format=Config [scss-files...]

linters:
  Indentation:
    enabled: false
  StringQuotes:
    enabled: false
  UrlQuotes:
    enabled: false

Files

Useful when you just want to open all offending files in an editor. This will just output the names of the files so that you can execute the following to open them all:

scss-lint --format=Files [scss-files...] | xargs vim

JSON

Outputs JSON with filenames and an array of issue objects.

{
  "test.css": [
    {"line": 2, "column": 1, "length": 2, "severity": "warning", "reason": "Prefer single quoted strings", "linter": "StringQuotes"},
    {"line": 2, "column": 1, "length": 1, "severity": "warning", "reason": "Line should be indented 0 spaces, but was indented 1 spaces", "linter": "Indentation"},
    {"line": 5, "column": 5, "length": 2, "severity": "warning", "reason": "Prefer single quoted strings", "linter": "StringQuotes"},
    {"line": 6, "column": 4, "length": 9, "severity": "warning", "reason": "URLs should be enclosed in quotes", "linter": "UrlQuotes"}
  ]
}

TAP

Outputs TAP version 13 format.

TAP version 13
1..5
ok 1 - ok1.scss
not ok 2 - not-ok1.scss:123:10 SCSSLint::Linter::PrivateNamingConvention
  ---
  message: Description of lint 1
  severity: warning
  data:
    file: not-ok1.scss
    line: 123
    column: 10
  ---
not ok 3 - not-ok2.scss:20:2 SCSSLint::Linter::PrivateNamingConvention
  ---
  message: Description of lint 2
  severity: error
  data:
    file: not-ok2.scss
    line: 20
    column: 2
  ---
not ok 4 - not-ok2.scss:21:3 SCSSLint::Linter::PrivateNamingConvention
  ---
  message: Description of lint 3
  severity: warning
  data:
    file: not-ok2.scss
    line: 21
    column: 3
  ---
ok 5 - ok2.scss

Stats

Outputs statistics about how many lints of each type were found, and across how many files. This reporter can help in cleaning up a large codebase, allowing you to fix and then enable one lint type at a time.

15  ColorKeyword                  (across  1 files)
15  ColorVariable                 (across  1 files)
11  StringQuotes                  (across 11 files)
11  EmptyLineBetweenBlocks        (across 11 files)
 5  Indentation                   (across  1 files)
 5  QualifyingElement             (across  2 files)
 4  MergeableSelector             (across  1 files)
--  ----------------------        -----------------
66  total                         (across 12 files)

Plugins

There are also formatters that integrate with third-party tools which are available as plugins.

Checkstyle

Outputs an XML document with <checkstyle>, <file>, and <error> tags. Suitable for consumption by tools like Jenkins with the Checkstyle plugin.

gem install scss_lint_reporter_checkstyle
scss-lint --require=scss_lint_reporter_checkstyle --format=Checkstyle [scss-files...]

<?xml version="1.0" encoding="utf-8"?>
<checkstyle version="1.5.6">
  <file name="test.css">
    <error line="2" severity="warning" message="Prefer single quoted strings" />
    <error line="2" severity="warning" message="Line should be indented 0 spaces, but was indented 1 spaces" />
    <error line="5" severity="warning" message="Prefer single quoted strings" />
    <error line="6" severity="warning" message="URLs should be enclosed in quotes" />
  </file>
</checkstyle>

Exit Status Codes

scss-lint tries to use semantic exit statuses wherever possible, but the full list of codes and the conditions under which they are returned is listed here for completeness.

Exit Status	Description
`0`	No lints were found
`1`	Lints with a severity of `warning` were reported (no errors)
`2`	One or more errors were reported (and any number of warnings)
`64`	Command line usage error (invalid flag, etc.)
`66`	One or more files specified were not found
`69`	Required library specified via `-r`/`--require` flag was not found
`70`	Unexpected error (i.e. a bug); please report it
`78`	Invalid configuration file; your YAML is likely incorrect
`80`	Files glob patterns specified did not match any files.

Linters

scss-lint is a customizable tool with opinionated defaults that helps you enforce a consistent style in your SCSS. For these opinionated defaults, we’ve had to make calls about what we think are the “best” style conventions, even when there are often reasonable arguments for more than one possible style.

Should you want to customize the checks run against your code, you can do so by editing your configuration file to match your preferred style.

» Linters Documentation

Custom Linters

scss-lint allows you to create custom linters specific to your project. By default, it will load linters from the .scss-linters in the root of your repository. You can customize which directories to load from via the plugin_directories option in your .scss-lint.yml configuration file. See the linters directory for examples of how to write linters. All linters loaded from directories in plugin_directories are enabled by default, and you can set their configuration in your .scss-lint.yml.

# .scss-linters/another_linter.rb

module SCSSLint
  class Linter::AnotherLinter < Linter
    include LinterRegistry

    ...
  end
end

# .scss-lint.yml
plugin_directories: ['.scss-linters', '.another_directory']

linters:
  AnotherLinter:
    enabled: true
    some_option: [1, 2, 3]

You can also load linters packaged as gems by specifying the gems via the plugin_gems configuration option. See the scss_lint_plugin_example for an example of how to structure these plugins.

If the gem is packaged with an .scss-lint.yml file in its root directory then this will be merged with your configuration. This provides a convenient way for organizations to define a single repo with their scss-lint configuration and custom linters and use them across multiple projects. You can always override plugin configuration with your repo’s .scss-lint.yml file.

# .scss-lint.yml
plugin_gems: ['scss_lint_plugin_example']

Note that you don’t need to publish a gem to Rubygems to take advantage of this feature. Using Bundler, you can specify your plugin gem in your project’s Gemfile and reference its git repository instead:

# Gemfile
gem 'scss_lint_plugin_example', git: 'git://github.com/cih/scss_lint_plugin_example'

As long as you execute scss-lint via bundle exec scss-lint, it should be able to load the gem.

Preprocessing

Sometimes SCSS files need to be preprocessed before being linted. This is made possible with two options that can be specified in your configuration file.

The preprocess_command option specifies the command to run once per SCSS file. The command can be specified with arguments. The contents of a SCSS file will be written to STDIN, and the processed SCSS contents must be written to STDOUT. If the process exits with a code other than 0, scss-lint will immediately exit with an error.

For example, preprocess_command: "cat" specifies a simple no-op preprocessor (on Unix-like systems). cat simply writes the contents of STDIN back out to STDOUT.

Metadata codeblocks like Jekyll Front Matter at the beginning of SCSS files can cause a syntax error when SCSS-Lint does not encounter Sass at the first line of the file, e.g. Invalid CSS after "@charset "utf-8"": expected "{", was ";". To search the first line for front matter’s triple dash delimiter ---, strip out the YAML codeblock and pass the result to SCSS-Lint with line numbers preserved, you can use preprocess_command: "sed '1{/^---$/{:a N;/---$/!ba;d}}'" – please note this sed command is valid for gnu-sed. If you are using the FreeBSD version of sed that ships with Mac OS X by default, it will throw an EOF error. You may solve this error by installing Homebrew, running brew install gnu-sed, and then substituting gsed for sed in the preprocess_command.

If only some SCSS files need to be preprocessed, you may use the preprocess_files option to specify a list of file globs that need preprocessing. Preprocessing only a subset of files should make scss-lint more performant.

Automated Code Review

Codacy

Codacy automates code reviews and monitors code quality on every commit and pull request. With Codacy you have scss-lint analysis out-of-the-box, and it is free for open source projects. It gives visibility into the technical debt and it can track code style and security issues, code coverage, code duplication, cyclomatic complexity and enforce best practices.

Editor Integration

Vim

You can have scss-lint automatically run against your SCSS files after saving by using the Syntastic plugin. If you already have the plugin, just add let g:syntastic_scss_checkers = ['scss_lint'] to your .vimrc.

IntelliJ

Install the SCSS Lint plugin for IntelliJ

Sublime Text

Install the Sublime scss-lint plugin.

Atom

Install the Atom scss-lint plugin. It is a part of the atomlinter project, so if you are already using other linter plugins, you can keep them in one place.

Emacs

Install and enable both scss-mode and flycheck-mode. You can enable automatic linting for scss-mode buffers with (add-hook 'scss-mode-hook 'flycheck-mode) in your init.el.

TextMate 2

If you use TextMate 2, you can install the SCSS-Lint.tmbundle bundle.

Visual Studio Code

If you use Visual Studio Code, you can install the scss-lint extension

Git Integration

If you’d like to integrate scss-lint into your Git workflow, check out our Git hook manager, overcommit.

Rake Integration

To execute scss-lint via a Rake task, ensure you have rake in your gem path (e.g. by adding to your Gemfile), and add the following to your Rakefile:

require 'scss_lint/rake_task'

SCSSLint::RakeTask.new

When you execute rake scss_lint, the above configuration is equivalent to just running scss-lint, which will lint all .scss files in the current working directory and its descendants.

You can customize the task by writing:

require 'scss_lint/rake_task'

SCSSLint::RakeTask.new do |t|
  t.config = 'custom/config.yml'
  t.args = ['--format', 'JSON', '--out', 'results.txt']
  t.files = Dir.glob(['app/assets', 'custom/*.scss'])
end

You can specify any command line arguments in the args attribute that are allowed by the scss-lint Ruby binary script. Each argument must be passed as an Array element, rather than one String with spaces.

You can also use this custom configuration with a set of files specified via the command line (note that this will not expand glob patterns):

# Single quotes prevent shell glob expansion
rake 'scss_lint[app/assets, custom/file-with-a-literal-asterisk-*.scss]'

Files specified in this manner take precedence over the files attribute initialized in the configuration above.

Maven Integration

Maven integration is available as part of the Sass maven plugin scss-lint since version 2.3 Check out the plugin documentation.

The Maven plugin comes with the necessary libraries included, a separate installation of ruby or scss-lint is not required.

Contributing

We love getting feedback with or without pull requests. If you do add a new feature, please add tests so that we can avoid breaking it in the future.

Speaking of tests, we use rspec, which can be run like so:

bundle exec rspec

After you get the unit tests passing, you probably want to see your version of scss-lint in action. You can use Bundler to execute your binary locally from within your project’s directory:

bundle exec bin/scss-lint

Community

All major discussion surrounding SCSS-Lint happens on the GitHub issues page.

You can also follow @scss_lint on Twitter.

Changelog

If you’re interested in seeing the changes and bug fixes between each version of scss-lint, read the SCSS-Lint Changelog.

Code of conduct

This project adheres to the Open Code of Conduct. By participating, you are expected to honor this code.

License

This project is released under the MIT license.