About Sass Private Members

The Sass specification allows us to create private mixins. These private mixins are usable and available only within a Sass module and cannot therefore be consumed outside this module.

To make a mixin private, simply prefix the mixin with the - or _ character.

For more information, see Sass documentation here: https://sass-lang.com/documentation/at-rules/use/#private-members

Issue with Stylelint & stylelint-config-standard-scss

When using Stylelint with stylelint-config-standard-scss on a Sass project containing private mixins, it may happen that the latter returns the following error:

✖  Expected mixin name to be kebab-case  scss/at-mixin-pattern

This is because the scss/at-mixin-pattern rule does not allow the use of the _ prefix.

Find out more here:

• Wrong kebab-case pattern for private members
• Default variable, mixin, and function patterns should not error on _ prefix used for private sass contructs
• Allow private mixins, placeholders and functions
• https://github.com/stylelint-scss/stylelint-config-standard-scss/blob/f6dfec8ef432a363984e1b3fed4db417328083e3/index.js#L37

Customizing the Stylelint rule

To overcome this, we can customise the Stylelint rule so that it uses the characters - or _ as a prefix and is ISO compliant with the Sass specification.

{
  "rules": {
    "scss/at-mixin-pattern": "^[-_]?([a-z][a-z0-9]*)(-[a-z0-9]+)*$",
  }
}