A Mimosa module for the JSCS Javascript linter
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This is a Mimosa module for linting Javascript code using JSCS.

Project status

This project is no longer being actively maintained.

This means that mimosa-jscs is not being tested with new versions of JSCS or Mimosa when they are released. See the section Compatibility below for a list of configurations that are known to work.

Please file an issue if you run into problems with other versions of JSCS or Mimosa.


Add jscs to your Mimosa project's list of modules and build the project. This will download the latest version of mimosa-jscs from npmjs.org.


To customize the linting you need to add a jscs configuration to your project's mimosa-config. mimosa-jscs is configured in the same way as other Mimosa linting tools such as mimosa-jshint. The configuration options and the default values are as follows:

jscs: {
    exclude: [],
    compiled: true,
    copied: true,
    vendor: false,
    executeAfterCompile: true,
    configFile: undefined,
    rules: {}

Which files are linted are controlled by the jscs.exclude, jscs.compiled, jscs.copied, and jscs.vendor options. These options work just like the corresponding options for the JSHint Mimosa plugin.

executeAfterCompile determines whether JSCS runs on code before or after it is compiled. This defaults to true which means that JSCS runs on compiled code. So, for instance, it would not run on CoffeeScript, instead it would run on the compiled JavaScript. You may find you want to run on pre-compiled code. Some compilers, like Babel will transform the style of the code when it compiles it. If running on the compiled output of Babel, JSCS will have many problems that cannot be avoided.

To configure JSCS, set either the jscs.rules property, the jscs.configFile property, or both. JSCS configuration options are described in detail in the JSCS documentation. For example, adding the following to your Mimosa config will make JSCS check that files end with a newline:

jscs: {
  rules: {
    requireLineFeedAtFileEnd: true

mimosa-jscs will pass the configuration to JSCS without validating its contents. The following configuration options have been verified to work:

  • Individual rules.
  • preset.
  • additionalRules. Rule paths are relative to the project root.
  • excludeFiles. In addition to the jscs.exclude property described above, mimosa-jscs also supports excluding files using excludeFiles in the JSCS configuration. This can come in handy if you want to share a JSCS configuration file between Mimosa and (for instance) an editor or IDE. Paths are relative to the project root.
  • maxErrors. In build mode, maxErrors is the maximum number of reported violations per build. In watch mode, maxErrors is per file.
  • errorFilter. Paths are relative to the project root.
  • esnext.
  • plugins. Paths are relative to the project root.
  • verbose.

The option fileExtensions is currently ignored.

jscs.configFile is the file name of a JSCS configuration file, absolute or relative to the project's root. In contrast to running JSCS from the command line, mimosa-jscs will not search other directories outside of your project for a configuration file. In particular, it will not search your home directory or the project directory's ancestors for a file named .jscsrc or .jscs.json. This is to make building independent of external files not part of the Mimosa project.

mimosa-jscs reads configuration files the same way as JSCS does, which means that the file format is determined from the file name:

  • If the file extension is .js the file is read as a Node module using Node's require.
  • If the file name is package.json the file is standard JSON and the configuration is in a property called jscsConfig.
  • If the file name is anything else with the extension .json the file is standard JSON.
  • Otherwise the file is commented JSON. Comments are standard Javascript comments and are stripped using strip-json-comments.

Both configFile and rules can be specified at the same time. In that case the configuration passed to JSCS will be the configuration found in the file overridden by anything found in rules. Note that in JSCS rules always override presets meaning that a rule configured in the file will still override a preset configured in rules.


To lint your Javascript using JSCS' Crockford preset, add the following to your project's Mimosa configuration:

jscs: {
  rules: {
    preset: 'crockford',

The following configuration will lint according to the Crockford preset and also check that all comments starts with a capital letter:

jscs: {
  rules: {
    preset: 'crockford',
    requireCapitalizedComments: true

To disable a rule, set it to null (this is standard JSCS behavior). The following configration will lint using the Crockford preset but disable indentation checking:

jscs: {
  rules: {
    preset: 'crockford',
    validateIndentation: null

The following module configuration will read the JSCS configuration from the project's package.json:

jscs: {
  configFile: 'package.json'

To lint using the Crockford preset, add the following to your package.json:

jscsConfig: {
    preset: 'crockford'


By default mimosa-jscs uses the latest version of JSCS that is compatible with a version it has been tested with. Compatibility is according to semver.

JSCS' approach to versioning is explained in the JSCS documentation. In short, changes in rules and presets that cause more (or less) code style violations to be reported are not considered breaking changes. To have better control of your JSCS linting you may want to use a specific version of JSCS.

To use a specific JSCS version add JSCS as dependency to your project. For example, to use JSCS version 1.8.0 type the following in your project root:

npm install --save-dev --save-exact jscs@1.8.0

If you try to use mimosa-jscs with a version of JSCS it has not been verified to be compatible with, npm install will fail with the following message:

npm ERR! peerinvalid The package jscs does not satisfy its siblings' peerDependencies requirements!

mimosa-jscs has been verified to work with the following JSCS versions: 1.3.0, 1.4.0, 1.4.3, 1.4.4, 1.4.5, 1.5.1, 1.5.2, 1.5.3, 1.5.4, 1.5.6, 1.5.7, 1.5.8, 1.5.9, 1.6.0, 1.6.1, 1.6.2, 1.7.0, 1.7.1, 1.7.2, 1.7.3, 1.8.0, 1.8.1, 1.9.0, 1.10.0, 1.11.0, 1.11.1, 1.11.2, 1.11.3, 1.12.0, 1.13.0, 1.13.1, and 2.0.0.

This module has been tested with Mimosa 2.3.x but should work with other versions of Mimosa as well.

Version history

  • 3.0.0 Added JSCS v2.0.0 to list of compatible versions. Starting with version 2.0.0 the API mimos-jscs uses is part of JSCS' public API and is covered by the semver versioning rules. This makes it much easier to manage compatibility, mimosa-jscs should now be compatible with any JSCS version 2.x.y. Updated the documentation accordingly.

    Major version bump because of JSCS' major version bump which may break compatibility.

  • 2.3.0 Added JSCS v1.13.0 and v1.13.1 to list of compatible versions.

  • 2.2.0 Added configuration option executeAfterCompile that makes it possible to configure if style of compiled resources are checked before or after compilation. Useful when compiling with Babel. Requested and implemented by dbashford.

  • 2.1.0 Added JSCS v1.12.0 to list of compatible versions. Removed Mimosa placeholder config property to be compatible with upcoming Mimosa v3.0.0. Minor documentation updates.

  • 2.0.0 JSCS is now an npm peer dependency which makes it possible for a user to choose JSCS version. Created unit tests for compatibility with JSCS versions from 1.3.0 up to 1.11.3. package.json contains a whitelist listing compatible versions.

    Major version bump because of the switch to a peer dependency for JSCS.

  • 1.1.0 Support JSCS option excludeFiles.

  • 1.0.4 Add documentation and test for esnext, additionalRules options.

  • 1.0.3 Support for the maxErrors option.

  • 1.0.2 Warn if neither rules nor config file is configured.

  • 1.0.1 Cosmetic changes.

  • 1.0.0 First functional version. Runs JSCS, loads configuration from mimosa config or file, configuration mimics mimosa-jshint.