@ama-styling/style-dictionary

Otter Style Dictionary

This package is an Otter Framework Module.

Description

This package exposes a set of Hooks and Modules for the Style Dictionary to enhance the capabilities of Design Tokens.

Get Started

Set up your Style Dictionary in your project thanks to the command:

ng add @ama-styling/style-dictionary

By default, the command will do the following updates:

• Add a dev dependency to the Style Dictionary package.
• Create a minimal config.mjs configuration file with the required setup for CSS and Metadata generation.
• Add the generate:theme and generate:metadata scripts in the project package.json.

You will then be able to customize this setup with your project's specifications:

• Customize the Style Dictionary configuration in the generated config.mjs file.
• Add extensions to your source Design Token via the enhancement mechanism.
• Configure output files thanks to the getTargetFiles helper.

Enhancement

Design Token Extensions

The Design Tokens format allows to provide the $extensions property to enhance the Token it is applied to.
The property can be applied to the Token directly as follows:

// colors.token.json
{
  "colors": {
    "primary": {
      "$value": "#000000",
      "$extensions": {
        "o3rPrivate": true
      }
    }
  }
}

or in a dedicated .extensions.json file (when the o3r/json-parser/extensions parser is loaded):

// color.token.json
{
  "colors": {
    "primary": {
      "$value": "#000000"
    }
  }
}

// custom.extensions.json
{
  "colors.primary": {
    "$description": "Primary private color",
    "$extensions": {
      "o3rPrivate": true
    }
  }
}

Available Otter Extensions

Extensions	Type	Description	Required hooks
o3rPrivate	boolean	Determine if the token is flagged as private	pre-processor: o3r/pre-processor/extensions formatter: o3r/css/variable
o3rImportant	boolean	Determine if the token should be flagged as important when generated	pre-processor: o3r/pre-processor/extensions formatter: o3r/css/variable
o3rScope	string	Scope to apply to the generated variable	pre-processor: o3r/pre-processor/extensions formatter: o3r/css/variable
o3rMetadata	CMS Metadata	Additional information to provide to the metadata if generated	pre-processor: o3r/pre-processor/extensions formatter: o3r/json/metadata
o3rUnit	string	Convert a numeric value from the specified unit to the new unit. It will add a unit to the tokens of type "number" for which the unit is not specified. In the case of complex types (such as shadow, transition, etc...), the unit will be applied to all numeric types they contain.	pre-processor: o3r/pre-processor/extensions transforms: o3r/transform/unit
o3rRatio	number	Ratio to apply to the previous value. The ratio will only be applied to tokens of type "number" or to the first numbers determined in "string" like types. In the case of complex types (such as shadow, transition, etc...), the ratio will be applied to all numeric types they contain.	pre-processor: o3r/pre-processor/extensions transforms: o3r/transform/ratio
o3rExpectOverride	boolean	Indicate that the token is expected to be overridden by external rules	pre-processor: o3r/pre-processor/extensions

[!WARNING] The required hooks need to be registered to the Style Dictionary configuration to fully support the extension.

Modules

Parsers

Name	Matching files	Description
o3r/json-parser/one-line-token	**/*.json	Allow dot notation Token in JSON file
o3r/json-parser/extensions	**/*.extensions.json	Parse file containing $extensions instructions to apply on top of Design Token

Pre-processor

Name	Description
o3r/pre-processor/extensions	Pre-processor to add the support of the $extensions instructions in the Token (or dedicated extensions.json file). This pre-processor is mandatory for any Otter hooks.

Transforms

Name	Type	Criteria	Description
o3r/transform/ratio	value	o3rRatio extension is provided	Apply the given o3rRatio to the numeric values of the Token(s) it refers to.
o3r/transform/unit	value	o3rUnit extension is provided	Replace the unit of the values of the Token(s) it refers to, by the provided o3rUnit.

Transform-groups

Name	Description
o3r/css/recommended	Extend the official CSS transform groups by adding o3r/transform/ratio and o3r/transform/unit

Formats

Name	Options	Description
o3r/css/variable	See css/variables options	Render CSS variable block (based on the built-in format) supporting additional Otter Extensions features.
o3r/json/metadata	See css/variables options (applied to defaultValue) - keepPrivate: include private variables	Render CMS style metadata.

Registration process

The different hooks/modules can be registered individually via the different register...() functions from StyleDictionary or all at once with the register function as follows:

import { register, baseConfig } from '@ama-styling/style-dictionary';

const sd = new StyleDictionary({
  ...baseConfig,
  // custom configs ...
});

register(sd); // Register all Otter modules

[!IMPORTANT] To be able to use any of the listed modules/hooks, they have to be registered to the StyleDefinition instance.

[!TIP] The helper baseConfig will provide the minimal configuration for Otter extension support.

Helpers

To enhance and facilitate the configuration of the StyleDictionary instance, the @ama-styling/style-dictionary exposes a set of helpers.

getTargetFiles

The getTargetFiles function is used to parameterize the generated file based on Design Token (following the same logic as $extensions):

// Example to generate the `color-primary-**` variables in `my-color-primary.css`

import { getTargetFiles } from '@ama-styling/style-dictionary';

const rule = {
  'color.primary': 'my-color-primary.css'
};

// or `const rule = {color: {primary: 'my-color-primary.css'}}`
// or `const rule = {'color.primary': {$extensions: {o3rTargetFile: 'my-color-primary.css'}}}`
// or `const rule = {'color: {primary': {$extensions: {o3rTargetFile: 'my-color-primary.css'}}}}`

const sd = new StyleDictionary({
  //...
  plateforms: {
    css: {
      files: [
        ...getTargetFiles({ rule, { format: 'css', defaultFile: 'default-file.css' } })
      ]
    }
  }
});

register(sd); // Register all Otter modules

[!NOTE] The format option will be applied to all the files provided to the getTargetFiles function (including defaultFile). defaultFile defines the default file where variables not matching any rule will be generated.

The helper function getTargetFiles is registering the filter into StyleDictionary with a unique ID.
This IDs can be retrieved as follows:

import { getTargetFiles } from '@ama-styling/style-dictionary';

const sd = new StyleDictionary();
const files = getTargetFiles({ rules, { styleDictionary: sd } });

/**
 * Filter IDs registered in {@link sd} Style Dictionary instance
 * @type {string[]}
 **/
const filterIds = files.map(({ filter }) => filter);

Advanced

Basic Node Configuration Example

// style-builder.mjs

import { register, getTargetFiles, baseConfiguration } from '@ama-styling/style-dictionary';
import StyleDictionary from 'style-dictionary';

// Rules to generate different CSS files according to Token name
const fileRules = {
  colors: 'style/colors.tokens.css',
  'components.panel': 'components/panel/panel.tokens.css'
}

const sd = new StyleDictionary({
  ...baseConfiguration, // Use basic Otter configuration setup
  usesDtcg: true, // Use Design Token Standard format

  source: ['tokens/*.tokens.json'], // Design Token files
  include: ['token.extensions.json'], // Custom extensions

  platforms: {
    // Generate CSS Files
    css: {
      options: {
        outputReferences: true // to output `--var: var(--other-var)` instead of the value of `--other-var`
      },
      transformGroup: 'o3r/css/recommended',
      files: [
        ...getTargetFiles(fileRules, { format: 'css' }),
        // default CSS file where generate variables
        { destination: 'style/default.tokens.css', format: 'css' }
      ]
    },
    cms: {
      options: {
        outputReferences: true
      },
      transformGroup: 'o3r/css/recommended',
      files: [
        { destination: 'style.metadata.json', format: 'o3r/json/metadata' }
      ]
    }
  }
});

// Register otter hooks/modules
register(sd);

if (process.env.CSS_ONLY){
  sd.buildPlatform('css');
} else {
  sd.buildAllPlatforms();
}

Can be run with the following command:

node ./style-builder.mjs