Design Tokens

Open Forms projects follow the NL Design System. We organize the design tokens in JSON files and use them in downstream projects like the SDK and the Open Forms backend project.

How it works

Specify the design tokens in JSON files, which are picked up and merged using the style-dictionary library. The resulting packages include various build targets, such as ES6 modules, CSS variables files, SASS vars... to be consumed in downstream projects.

The draft Design Token Format drives the structure of these design tokens.

Usage

Using tokens

If you are only consuming the design tokens, the easiest integration path is adding the NPM package as dependency to your project:

npm install --save-dev @open-formulieren/design-tokens

Then, import the desired build target artifact and run your usual build chain.

Developing and using tokens

If you actively need to add or change design tokens, we recommend installing the package locally and using npm workspaces or npm link for the least-friction experience. For Open Forms specifically, we include the package as a git-submodule and leverage npm workspaces with instructions in the downstream projects.

This allows you to create atomic PRs with design token changes, while being able to develop against the newest changes.

Run:

npm start

to start the watcher which will re-build on changes.

Naming pattern

Because of the way style-dictionary works, you have to pay close attention to the structure of the tokens. E.g. if you have two tokens definition files like:

{
  "of": {
    "color": {
      "fg": {"value": "#000000"}
    }
  }
}

{
  "of": {
    "color": {
      "fg": {
        "muted": {"value": "#000000"}
      }
    }
  }
}

Then only --of-color-fg will be emitted since the merged object sees a value key at the of.color.fg path.

You can usually avoid this by sticking to a structure adhering to:

<prefix>.<component>.<modifier>.<UIState>.<CSSProperty>

Where UIState can be blank or a value like hover, active...

Alternatively, if the structure is not that important, you can put the tokens on the same level, e.g.:

{
  "of": {
    "color": {
      "fg-muted": {"value": "#000000"}
    }
  }
}

The latter form is harder to keep track off across files though.

Release flow

We don't let npm apply the git tags when releasing a new version, instead follow this process:

npm version minor
git commit -am ":bookmark: Bump to version <newVersion>"
git tag "<newVersion>"
git push origin main --tags

If you have PGP keys set up, you can use them for the git tag operation.

The CI pipeline will then publish the new version to npmjs.