stylelint-declaration-use-variable-or-custom-fn

A stylelint plugin that check the use of scss, less or custom css variable on declaration. Either used with '$', map-get(), '@', 'var(--var-name)', or with a user-specified custom function(s).

Installation

npm install stylelint-declaration-use-variable-or-palette

Be warned: v1.0.0+ is only compatible with stylelint v3+.

Usage

Add it to your stylelint config plugins array, then add "declaration-use-variable-or-custom-fn" to your rules, specifying the property for which you want to check the usage of variable.

Basic usage:

// .stylelintrc
{
  "plugins": [
    "stylelint-declaration-use-variable-or-custom-fn"
  ],
  "rules": {
    // ...
    "chrismendis/declaration-use-variable-or-custom-fn": "color",
    // ...
  }
}

Multiple properties

Multiple properties can be watched by passing them inside array. Regex can also be used inside arrays.

// .stylelintrc
"rules": {
  // ...
  "chrismendis/declaration-use-variable-or-custom-fn": [["/color/", "z-index", "font-size"]],
  // ...
}

Regex support

Passing a regex will watch the variable usage for all matching properties. This rule will match all CSS properties while ignoring Sass and Less variables.

// .stylelintrc
"rules": {
  // ...
  "chrismendis/declaration-use-variable-or-custom-fn": "/color/",
  // ...
}

Custom function support

Passing an object with properties props and functionNames will check the variable or custom function usage for all matching properties of props.

// .stylelintrc
"rules": {
  // ...
  "chrismendis/declaration-use-variable-or-custom-fn": {comparison: "color", functionNames: ["myCustomFn"]},
  // ...
}

Details

Preprocessers like scss, less uses variables to make the code clean, maintainable and reusable. But since developers are lazy they might get a chance to miss the use of variables in styling code and that kinda sucks.

$some-cool-color: #efefef;
 
.foo {
    display: inline-block;
    text-align: center;
    color: #efefef; // Wait a min! there should be a variable. 
}

Supported scss variables

Scss variables using '$' notation and map-get are supported

// Simple variables 
$some-cool-color: #efefef;
$some-integer: 123;
$some-pixels: 4px;
 
color: $some-cool-color;
 
// Using map-get 
$cool-colors: (
    blue: #3ea1ec,
    red: #eb5745,
);
 
color: map-get($cool-colors, blue);
 

Supported color functions

If you plan to level-up the usage of your variables by the usage of fancy color-functions - you can!

Instead of a direct variable usage like this:

$white: #fff;
 
.foo {
  color: $white;
}

You could also do things like:

.foo {
  color: color($white shade(10%));
}

This will still be seen as a valid code by the plugin. As a side-note, it doesn't matter what kind of variable-syntax you are using in the color function itself - if the line starts with color( then it is seen as valid.

If you contribute and wonder about the check for color( - it couldn't be done via regex because not only values will be passed to the plugin, but also property names. For some reason, the plugin just dies if you start extending the regex to look for "color". So it must be done via extra-if-check.