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A tool for managing design decision outputs for different platforms
JavaScript Jsonnet Other
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Mole is a platform agnostic preprocessor that allows you to create your own design system framework.

It's main features are:

  • Bare bones library to create your own framework
  • Multiple use cases from creating design tokens, to CSS frameworks, to something else entirely
  • Simple, flexible, automatic template choosing, optional named outputs

Mole is currently in alpha and it's features are still evolving. If you'd like to contribute to it's progress please see the contributing guidelines for how you can help.


Setup your project and install mole as a dependency. Use @next for the next alpha release.

npm install mole@next --save-dev

Build output files using

Configure mole using one of the methods below.

See the examples for different ways of configuring your project.


By default mole will look for a file called mole.config.js at the root of your project, you can override this using mole.config().

An example of a config file

// mole.config.js
module.exports = {
    theme: 'theme.js', // The path of your theme file (supports .js and .jsonnet) 
    model: ['model-name'], // The name or path of any models you want to use (optional)
    template: ['template-name'], // The name or path of any templates you want to use
    output: [ // You can have one or more outputs
        { css: { file: 'styles.css' } }, 
        { ios: { file: 'styles.h' } },
        { android: { file: 'styles.xml' } }

An example of manually setting the location of the config file


Config Options

Property Type Description
theme {String} (Optional) The location of your theme data. Mole supports js, and jsonnet.
model {String} (Optional) Can be either a named model, a dir or a path to a js file which exports a callback. When a dir is used it will look for files or sub directories who's name matches a named output. An array can be used to specify multiple models.
template {String} Can be either a named template, a dir, or a path to a js file which exports a function or template string, or a njk file which contains Nunjucks template code. When a dir is used it will look for sub directories who's name matches a named output and then look for file names matching a top level key inside data. Failing this it will look for files who's name matches a named output inside the directory. Additionally you may wish to name a file index and that will be used instead. An array can be used to specify multiple templates.
output {Object} An object with properties specifying where and how to process the output. You can specify a different template or model for each output. Create a named output by surrounding it in a key. An array can be used to specify multiple outputs.


A theme is a file used to describe different design decisions, characteristics, traits or tokens. Mole is fairly unopinionated about how you use it so you can structure your theme data how you like. In fact a theme is completely optional if you prefer.

Below is a trivial example of a theme

    font: {
        size: [

Theme data is accessible inside models and is immutable from inside them. When you create a model this returns an object which updates the main model and is then available to use by templates when they are rendered.

To avoid logic responsible for describing certain design characteristics being stored in models, you can can describe theme data using a more expressive method using Jsonnet which includes functions from it's standard library.

Example using Jsonnet

    font: {
        size: [
            std.ceil(16 * std.pow($.number['golden ratio'], n))
            for n in std.range(0, 5)


Models allow you to create a data structure from theme data so it can be used by different templates for different platforms and languages.

When more than one model is assigned to an output the data from each model is merged together.

To create a named model

mole.create('model', 'model-name', (theme) => {

    // Create a data model by modifying the theme data
    model =
    return model


Templates allow you to format data for a specific platform or language. You can create templates by either using template strings (using Nunjucks) or a function.

When multiple templates are specified the strings from each template are merged into one.

To create a template using a function

mole.create('template', 'template-name', (theme, model) => {

    let utility = model.font.size
    let string = ''

    for (let i = 0; i < utility.length; i++) {
        let value = utility[i]
		string += `.$font-${i} {\n`
		string += ` font-size: ${value}\n`
		string += `}\n`
    return string

To create a template using a template string

mole.create('template', 'template-name',

    `.font-{{modifier}} {
        font-size: {{value}};


Property Type Description
mole.config() {String} or {Object} Set the configuration
mole.theme() {String} or {Object} Set or update the theme data
mole.create() {Type}, {Name}, {Callback} Create a model or template
mole.render() Returns an array of rendered templates Build the output files


To install

npm install mole@next --save-dev

To run/compile

npm run build

To test

npm run test

To test and watch for changes

npm run dev
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