@tokens-studio/sd-transforms

Style Dictionary Transforms for Tokens Studio

This library is currently in beta.

This package contains custom transforms for Style-Dictionary, to work with Design Tokens that are exported from Tokens Studio:

Generic:

• Expands composition tokens into multiple, optionally also does so for typography, border and shadow tokens -> parser
• Maps token descriptions to comments -> ts/descriptionToComment
• Check and evaluate Math expressions (transitive) -> ts/resolveMath
• Transform dimensions tokens to have px as a unit when missing (transitive) -> ts/size/px
• Transform opacity from % to number between 0 and 1 -> ts/opacity
• Transform lineheight from % to unitless (150% -> 1.5) -> ts/size/lineheight
• Transform fontweight from keynames to fontweight numbers (100, 200, 300 ... 900) -> ts/type/fontWeight
• Transform color modifiers from Tokens Studio to color values -> ts/color/modifiers

CSS:

• Transform letterspacing from % to em -> ts/size/css/letterspacing
• Transform colors to rgba() format -> ts/color/css/hexrgba
• Transform typography objects to CSS shorthand -> ts/typography/css/shorthand
• Transform Tokens Studio shadow objects to CSS shadow shorthand -> ts/shadow/css/shorthand
• Transform border objects to CSS border shorthand -> ts/border/css/shorthand

Android:

• Transform typography objects to Android Compose shorthand -> ts/typography/compose/shorthand

Registers the generic and CSS transforms, in addition to name/cti/camel for naming purposes, as a transform group called tokens-studio.

Installation

With NPM:

npm install @tokens-studio/sd-transforms

Usage

Note: this library is available both in CJS and ESM

const { registerTransforms } = require('@tokens-studio/sd-transforms');

// will register them on StyleDictionary object
// that is installed as a dependency of this package.
registerTransforms();

Can also import in ESM if needed.

Using the transforms

In your Style-Dictionary config, you can either use the tokens-studio transformGroup or the separate transforms (all of the names of those are listed):

{
  "source": ["**/*.tokens.json"],
  "platforms": {
    "css": {
      "transformGroup": "tokens-studio",
      "buildPath": "build/css/",
      "files": [
        {
          "destination": "variables.css",
          "format": "css/variables"
        }
      ]
    }
  }
}

More fine-grained control is possible, every transformation is available as a raw JavaScript function for you to create your own Style-Dictionary transformer out of.

const { transformDimension } = require('@tokens-studio/sd-transforms');
const StyleDictionary = require('style-dictionary');

StyleDictionary.registerTransform({
  name: 'my/size/px',
  type: 'value',
  transitive: true,
  matcher: token => ['fontSizes', 'dimension', 'borderRadius', 'spacing'].includes(token.type),
  transformer: token => transformDimension(token.value),
});

Options

You can pass options to the registerTransforms function.

registerTransforms({
  expand: {
    composition: false,
    typography: true,
    border: (token, filePath) =>
      token.value.width !== 0 && filePath.startsWith(path.resolve('tokens/core')),
    shadow: false,
  },
});

Options:

name	type	required	default	description
expand	boolean | ExpandOptions	❌	See props below	false to not register the parser at all. By default, expands composition tokens. Optionally, border, shadow and typography as well.
expand.composition	boolean | ExpandFilter	❌	true	Whether or not to expand compositions. Also allows a filter callback function to conditionally expand per token/filePath
expand.typography	boolean | ExpandFilter	❌	false	Whether or not to expand typography. Also allows a filter callback function to conditionally expand per token/filePath
expand.shadow	boolean | ExpandFilter	❌	false	Whether or not to expand shadows. Also allows a filter callback function to conditionally expand per token/filePath
expand.border	boolean | ExpandFilter	❌	false	Whether or not to expand borders. Also allows a filter callback function to conditionally expand per token/filePath

Note: you can also import and use the expandComposites function to run the expansion on your token object manually. Handy if you have your own parsers set up (e.g. for JS files), and you want the expansions to work there too.

Full example

node build-tokens.js

build-tokens.js:

const { registerTransforms } = require('@tokens-studio/sd-transforms');
const StyleDictionary = require('style-dictionary');

registerTransforms(StyleDictionary);

const sd = StyleDictionary.extend({
  source: ['**/*.tokens.json'],
  platforms: {
    js: {
      transformGroup: 'tokens-studio',
      buildPath: 'build/js/',
      files: [
        {
          destination: 'variables.js',
          format: 'javascript/es6',
        },
      ],
    },
    css: {
      transforms: [
        'ts/descriptionToComment',
        'ts/size/px',
        'ts/opacity',
        'ts/size/css/letterspacing',
        'ts/size/lineheight',
        'ts/type/fontWeight',
        'ts/resolveMath',
        'ts/typography/css/shorthand',
        'ts/border/css/shorthand',
        'ts/shadow/css/shorthand',
        'ts/color/css/hexrgba',
        'ts/color/modifiers',
        'name/cti/kebab',
      ],
      buildPath: 'build/css/',
      files: [
        {
          destination: 'variables.css',
          format: 'css/variables',
        },
      ],
    },
  },
});

sd.cleanAllPlatforms();
sd.buildAllPlatforms();

Note: make sure to choose either the full transformGroup, OR its separate transforms, so you can adjust or add your own. Combining a transformGroup with a transforms array can give unexpected results.