JsNik is node library for generating Mapnik configuration in JS. This adds all the benefits of scripting like preventing repetition, programatic style generation, etc.
NOTE We recommend to use JsxNik instead.
npm install jsnik
Mapnik configuration in JS: https://github.com/FreemapSlovakia/freemap-mapnik/tree/master/style
Resulting map: https://www.freemap.sk/?map=10/48.725397/19.414215&layers=X