@tokens-studio/sd-transforms

Style Dictionary Transforms for Tokens Studio

Note: this README contains examples that assume latest version of this package & v4 style-dictionary latest prerelease.

Table of contents

• Installation
• Compatibility
• Usage
  • Using the preprocessor
  • Using expand
  • Using the transforms
  • Custom Transform Group
  • Options
• Theming
  • Themes complete example
  • Multi-dimensional theming
• Transforms
• Troubleshooting

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

Generic:

• Optionally excludes parent keys from your tokens file, e.g. when using single-file export from Tokens Studio Figma plugin -> preprocessor
• 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/typography/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 shadow "type" property "innerShadow" to "inset" -> ts/shadow/innerShadow

Android:

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

Registers the generic and CSS transforms as a transform group called tokens-studio.

Installation

With NPM:

npm install @tokens-studio/sd-transforms

Compatibility

This package is to be used in combination with Style Dictionary.

There are some caveats however, with regards to which versions of Style Dictionary are compatible with which versions of this package:

Style Dictionary	sd-transforms
3.0.0 - 4.0.0-prerelease.1	<= 0.12.2
4.0.0-prerelease.2 - 4.0.0-prerelease.18	0.13.0 - 0.14.4
4.0.0-prerelease.18 - 4.0.0-prerelease.26	0.13.0 - 0.15.2
>= 4.0.0-prerelease.27	>= 0.16.0
>= 4.0.0	>= 1.0.0

Now that Style Dictionary v4 is released, and sd-transforms v1 is released and out of alpha state,both APIs are stable and the recommendation is to use these.

Usage

[!NOTE] This library is only available in ESM

import { register } from '@tokens-studio/sd-transforms';
import StyleDictionary from 'style-dictionary';

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

const sd = new StyleDictionary({
  // make sure to have source match your token files!
  // be careful about accidentally matching your package.json or similar files that are not tokens
  source: ['tokens/**/*.json'],
  preprocessors: ['tokens-studio'], // <-- since 0.16.0 this must be explicit
  platforms: {
    css: {
      transformGroup: 'tokens-studio', // <-- apply the tokens-studio transformGroup to apply all transforms
      transforms: ['name/kebab'], // <-- add a token name transform for generating token names, default is camel
      buildPath: 'build/css/',
      files: [
        {
          destination: 'variables.css',
          format: 'css/variables',
        },
      ],
    },
  },
});

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

To run it use the following command

node build-output.js

Using the preprocessor

You must add the 'tokens-studio' preprocessor explicitly in the configuration:

{
  "source": ["tokens/**/*.json"],
  "preprocessors": ["tokens-studio"],
  "platforms": {}
}

This allows fontStyles to be extracted when they are embedded in fontWeights, aligns Tokens Studio token types with DTCG token types, and allows excluding parent keys for single-file Tokens Studio exports.

[!TIP] The align types part of the preprocessor aligns Tokens Studio token types to DTCG token types. The original Tokens Studio type in this scenario will be stored at $extensions['studio.tokens'].originalType if this happens. This allows you to use the original type e.g. for token filtering/matching for your custom transforms.

Using "Expand"

Expand used to be an sd-transforms exclusive feature but has moved to Style Dictionary itself under a slightly different API. This made sense due to object-value tokens being part of the DTCG spec and no longer a Tokens Studio specific feature.

When using the expand feature of Style Dictionary to expand object-value (composite) tokens, you should pass our additional expandTypesMap for Tokens Studio tokens, because these are slightly different from the DTCG tokens:

• shadow tokens are called boxShadow and their offsetX and offsetY props are called x and y respectively.
• typography tokens have some additional properties in Tokens Studio:
  • paragraphSpacing -> dimension
  • paragraphIndent -> dimension
  • textDecoration -> other
  • textCase -> other

Due to the Style Dictionary object-value tokens expansion happening before custom preprocessors such as the sd-transforms preprocessor, which aligns Tokens Studio token types with DTCG token types, this has to be configured like so:

import StyleDictionary from 'style-dictionary';
import { expandTypesMap } from '@tokens-studio/sd-transforms';

const sd = new StyleDictionary({
  source: ['tokens/**/*.json'],
  preprocessors: ['tokens-studio'],
  expand: {
    typesMap: expandTypesMap,
  },
  platforms: {},
});

Using the transforms

{
  "source": ["tokens/**/*.json"],
  "preprocessors": ["tokens-studio"],
  "platforms": {
    "css": {
      "transformGroup": "tokens-studio",
      "transforms": ["name/kebab"],
      "buildPath": "build/css/",
      "files": [
        {
          "destination": "variables.css",
          "format": "css/variables"
        }
      ]
    },
    "scss": {
      "transforms": ["ts/size/px", "ts/opacity", "name/kebab"],
      "buildPath": "build/scss/",
      "files": [
        {
          "destination": "variables.scss",
          "format": "scss/variables"
        }
      ]
    }
  }
}

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

import { transformDimension } from '@tokens-studio/sd-transforms';
import StyleDictionary from 'style-dictionary';

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

Custom Transform Group

[!NOTE] From Style-Dictionary 4.0.0-prerelease.18, transformGroup and transforms can now be combined in a platform inside your config.

You can create a custom transformGroup that includes the individual transforms from this package. If you wish to use the transformGroup, but adjust or remove a few transforms, your best option is to create a custom transform group:

import { getTransforms } from '@tokens-studio/sd-transforms';
import StyleDictionary from 'style-dictionary';

// Register custom tokens-studio transform group
// without 'px' being added to numbers without a unit
// and also adding 'name/constant' for the token names
StyleDictionary.registerTransformGroup({
  name: 'custom/tokens-studio',
  // default value for platform is css, specifies which Tokens Studio transforms for which platform to grab
  transforms: [...getTransforms({ platform: 'css' }), 'name/constant'].filter(
    transform => transform !== 'ts/size/px',
  ),
});

Note that you can also manually grab some of the SD built-in transforms by using StyleDictionary.hooks.transformGroups or StyleDictionary.hooks.transforms

Options

You can pass options to the register function.

register(StyleDictionary, {
  excludeParentKeys: true,
  platform: 'css',
  name: 'tokens-studio',
  'ts/color/modifiers': {
    format: 'hex',
  },
});

Options:

name	type	required	default	description
excludeParentKeys	boolean	❌	false	Whether or not to exclude parent keys from your token files
platform	'css'|'compose'	❌	css	Which platform to use the transforms for.
name	string	❌	tokens-studio	Under which name to register the transformGroup
withSDBuiltins	boolean	❌	true	Whether to append the Style Dictionary built-in transformGroup transforms for the configured platform into the tokens-studio transformGroup.
alwaysAddFontStyle	boolean	❌	false	Whether or not to always add a 'normal' fontStyle property to typography tokens which do not have explicit fontStyle
['ts/color/modifiers']	ColorModifierOptions	❌	See props below	Color modifier options
['ts/color/modifiers'].format	ColorModifierFormat	❌	undefined	Color modifier output format override ('hex' | 'hsl' | 'lch' | 'p3' | 'srgb'), uses local format or modifier space as default

[!NOTE] You can also import and use the parseTokens function to run the parsing steps on your tokens object manually. Handy if you have your own preprocessors set up (e.g. for JS files), and you want the preprocessor-based features like composites-expansion to work there too.

Theming

Themes: complete example

You might be using Themes in the PRO version of Tokens Studio.

Here's a full example of how you can use this in conjunction with Style Dictionary and sd-transforms:

Run this script:

import { register } from '@tokens-studio/sd-transforms';
import StyleDictionary from 'style-dictionary';
import { promises } from 'fs';

register(StyleDictionary, {
  /* options here if needed */
});

async function run() {
  const $themes = JSON.parse(await promises.readFile('$themes.json', 'utf-8'));
  const configs = $themes.map(theme => ({
    source: Object.entries(theme.selectedTokenSets)
      .filter(([, val]) => val !== 'disabled')
      .map(([tokenset]) => `${tokenset}.json`),
    preprocessors: ['tokens-studio'], // <-- since 0.16.0 this must be explicit
    platforms: {
      css: {
        transformGroup: 'tokens-studio',
        transforms: ['name/kebab'],
        files: [
          {
            destination: `vars-${theme.name}.css`,
            format: 'css/variables',
          },
        ],
      },
    },
  }));

  async function cleanAndBuild(cfg) {
    const sd = new StyleDictionary(cfg);
    await sd.cleanAllPlatforms(); // optionally, cleanup files first..
    await sd.buildAllPlatforms();
  }
  await Promise.all(configs.map(cleanAndBuild));
}

run();

Multi-dimensional Theming

If you're using Tokens Studio multi-dimensional theming, you'll have to run some logic to create permutations of those multiple dimensions of themes. We export a function called permutateThemes that allows passing the data from your $themes.json, and will give back an object with all the different permutations.

For example, consider the following multi-dimensional theme hierarchy (Group > Theme > TokenSet):

mode
  |-- light
  |     `-- core, light, theme
  `-- dark
        `-- core, dark, theme

brand
  |-- casual
  |     `-- core, casual
  `-- business
        `-- core, business

Here we have two groups:

1. mode: has two themes light & dark
2. brand: has two themes casual & business

Running permutateThemes on these themes will generate 4 theme combinations:

1. light_casual
2. dark_casual
3. light_business
4. dark_business

See details below:

import { permutateThemes } from '@tokens-studio/sd-transforms';
import fs from 'fs';

/**
 * Input:
 * [
 *  {
 *    name: 'light'
 *    group: 'mode',
 *    selectedTokensets: {
 *      'core': 'source',
 *      'light': 'enabled',
 *      'theme': 'enabled'
 *    }
 *  },
 *  {
 *    name: 'dark'
 *    group: 'mode',
 *    selectedTokensets: {
 *      'core': 'source',
 *      'dark': 'enabled',
 *      'theme': 'enabled'
 *    }
 *  },
 *  {
 *    name: 'casual'
 *    group: 'brand',
 *    selectedTokensets: {
 *      'core': 'source',
 *      'casual': 'enabled'
 *    }
 *  },
 *  {
 *    name: 'business'
 *    group: 'brand',
 *    selectedTokensets: {
 *      'core': 'source',
 *      'business': 'enabled'
 *    }
 *  }
 * ]
 *
 * Output:
 * {
 *   light_casual: ['core', 'light', 'theme', 'casual'],
 *   dark_casual: ['core', 'dark', 'theme', 'casual'],
 *   light_business: ['core', 'light', 'theme', 'business'],
 *   dark_business: ['core', 'dark', 'theme', 'business'],
 * }
 */
permutateThemes(JSON.parse(fs.readFileSync('$themes.json', 'utf-8')), { separator: '_' });

Note that it is a best practice to generate standalone output files for each theme combination. In the example above, we should generate 4 standalone CSS file light_casual.css, dark_casual.css, light_business.css and dark_business.css. We can then switch between them to change themes. Avoid generating all this output in a single file and trying to select different sections of the file. This will increase the file size as the number of theme combinations grows resulting in increased load times.

Full example with multi-dimensional themes:

import { register, permutateThemes } from '@tokens-studio/sd-transforms';
import StyleDictionary from 'style-dictionary';
import { promises } from 'fs';

register(StyleDictionary, {
  /* options here if needed */
});

async function run() {
  const $themes = JSON.parse(await promises.readFile('$themes.json', 'utf-8'));
  const themes = permutateThemes($themes, { separator: '_' });
  const configs = Object.entries(themes).map(([name, tokensets]) => ({
    source: tokensets.map(tokenset => `${tokenset}.json`),
    preprocessors: ['tokens-studio'], // <-- since 0.16.0 this must be explicit
    platforms: {
      css: {
        transformGroup: 'tokens-studio',
        transforms: ['name/kebab'],
        files: [
          {
            destination: `vars-${name}.css`,
            format: 'css/variables',
          },
        ],
      },
    },
  }));

  async function cleanAndBuild(cfg) {
    const sd = new StyleDictionary(cfg);
    await sd.cleanAllPlatforms(); // optionally, cleanup files first..
    await sd.buildAllPlatforms();
  }
  await Promise.all(configs.map(cleanAndBuild));
}

run();

You can find a variation of this example here. It outputs a CSS file for every theme combination for every component, e.g. button-business-blue.css, date-picker-business-blue.css and so on. This caters to use cases where component-level tokens as required, e.g. when implementing Web Components.

Transforms

ts/descriptionToComment

This transform maps token descriptions into comments.

Also converts carriage return \r into \n and \r\n into just \n.

matches: All tokens that have a description property.

before

{
  "token": {
    ...
    "description": "Some description about the token",
  }
}

after

{
  "token": {
    ...
    "description": "Some description about the token",
    "comment": "Some description about the token",
  }
}

ts/resolveMath

This transform checks and evaluates math expressions

matches: All tokens that have string values.

You can adjust to how many decimals the result should be rounded using PlatformConfig.mathFractionDigits:

{
  "source": ["tokens.json"],
  "platforms": {
    "css": {
      "mathFractionDigits": 3,
      "transformGroup": "tokens-studio",
      "files": [
        {
          "format": "css/variables",
          "destination": "output.css"
        }
      ]
    }
  }
}

before

{
  "token-one": {
    ...
    "value": "4*1.5px 4*1.5px 4*1.5px"
  },
  "token-two": {
    ...
    "value": "4 * 7"
  }
}

after

{
  "token-one": {
    ...
    "value": "6px 6px 6px"
  },
  "token-two": {
    ...
    "value": "28"
  }
}

ts/size/px

This transform adds px as a unit when dimension-like tokens do not have a unit.

matches: token.type is one of ['fontSize', 'dimension', 'border', 'typography', 'shadow']

before

{
  "token": {
    "type": "dimension",
    "value": 4
  }
}

after

{
  "token": {
    "type": "dimension",
    "value": "4px"
  }
}

ts/opacity

This transforms opacity token values declared with % into a number between 0 and 1.

matches: token.type is 'opacity'

before

{
  "token": {
    "type": "opacity",
    "value": "50%"
  }
}

after

{
  "token": {
    "type": "opacity",
    "value": 0.5
  }
}

ts/size/lineheight

This transforms line-height token values declared with % into a unitless value.

matches: token.type is 'lineHeight' or token.type is 'typography'

before

{
  "token": {
    "type": "lineHeights",
    "value": "50%"
  }
}

after

{
  "token": {
    "type": "lineHeights",
    "value": 0.5
  }
}

ts/typography/fontWeight

This transforms fontweight from keynames to fontweight numbers.

matches: token.type is 'fontWeight' or token.type is 'typography'

before

{
  "token-one": {
    "type": "fontWeights",
    "value": "Bold"
  },
  "token-two": {
    "type": "fontWeights",
    "value": "Light"
  }
}

after

{
  "token-one": {
    "type": "fontWeights",
    "value": "700"
  },
  "token-two": {
    "type": "fontWeights",
    "value": "300"
  }
}

ts/color/modifiers

This transforms color modifiers from Tokens Studio to color values.

matches: token.type is 'color' and has token.$extensions['studio.tokens'].modify

before

{
  "token-one": {
    "value": "#C14242",
    "type": "color",
    "$extensions": {
      "studio.tokens": {
        "modify": {
          "type": "lighten",
          "value": "0.2",
          "space": "srgb"
        }
      }
    }
  },
  "token-two": {
    "value": "#C14242",
    "type": "color",
    "$extensions": {
      "studio.tokens": {
        "modify": {
          "type": "darken",
          "value": "0.2",
          "space": "hsl"
        }
      }
    }
  }
}

after

{
  "token-one": {
    "value": "rgb(80.5% 40.7% 40.7%)",
    "type": "color"
  },
  "token-two": {
    "value": "hsl(0 50.6% 40.6%)",
    "type": "color"
  }
}

ts/size/css/letterspacing

This transforms letter-spacing token values declared with % to a value with em.

matches: token.$extensions['studio.tokens'].originalType is 'letterSpacing' or token.type is 'typography'

before

{
  "token": {
    "type": "letterSpacing",
    "value": "50%"
  }
}

after

{
  "token": {
    "type": "letterSpacing",
    "value": "0.5em"
  }
}

ts/color/css/hexrgba

This transforms color token values with Figma's "hex code RGBA" into actual rgba() format

matches: token.type is 'color'

before

{
  "token": {
    "type": "color",
    "value": "rgba(#ABC123, 0.5)"
  }
}

after

{
  "token": {
    "type": "color",
    "value": "rgba(171, 193, 35, 0.5)"
  }
}

ts/shadow/innerShadow

This transforms shadow tokens to ensure that the type property gets converted from innerShadow to inset (CSS compatible).

matches: token.type is 'shadow'

before

{
  "token": {
    "type": "color",
    "value": {
      "offsetX": "0",
      "offsetY": "4px",
      "blur": "10px",
      "color": "#000",
      "type": "innerShadow"
    }
  }
}

after

{
  "token": {
    "type": "color",
    "value": {
      "offsetX": "0",
      "offsetY": "4px",
      "blur": "10px",
      "color": "#000",
      "type": "inset"
    }
  }
}

Not sure how to fix your issue?

Create a reproduction by:-

1. Open the configurator tool link
2. Upload your tokens and add your style dictionary config and transforms
3. Copy the URL as it will include your settings
4. Join our Slack link
5. Open style-dictionary-configurator channel
6. Create a thread about your issue and paste your reproduction link inside it

Changelog

1.2.8

Patch Changes

• 5de4025: Addressed issue #316 about letterSpacing. LetterSpacing is no longer a dimension token. Also, the expand composition test token has been modify to test if the letterSpacing still works properly.