Need examples of registerFilter for documentation update

[gearsandcode]

I'd be happy to take care of the #286, but wasn't able to get filter working. If anyone can provide working examples of filter in use, that would be awesome.

Here's my pseudo code that I couldn't get working:

"platforms": {
    "web/scss": {
            "transformGroup": "tokens-scss",
            "buildPath": `dist/${brand}/web/`,
            "prefix": "",
            "files": [
                {
                    "destination": `scss/${category}-tokens.scss`,
                    "format": "scss/variables",
                    "filter": "filter-alias"
                }
            ]
        }
}...

StyleDictionaryPackage.registerFilter({
    name: 'filter-alias',
    matcher: function(prop) {
        return prop.attributes.type !== 'alias';
    }
})

[dbanksdesign]

I made this quick example (simplified from your code a bit):

const StyleDictionary = require('style-dictionary');

StyleDictionary.registerFilter({
  name: 'filter-alias',
  matcher: function(prop) {
    return prop.attributes.type !== 'alias';
  }
});

StyleDictionary.extend({
  "source": ["tokens/**/*.json"],
  "platforms": {
    "web/scss": {
      "transformGroup": "scss",
      "buildPath": "dist/",
      "prefix": "",
      "files": [
        {
          "destination": "scss/variables.scss",
          "format": "scss/variables",
          "filter": "filter-alias"
        }
      ]
    }
  }
}).buildAllPlatforms();

And it works. One thing to note is the filter will include only when the matcher returns true. This is definitely something we should add to the docs though, filtering is not very well documented yet.