Adding functions to existing JS app

I use the open source web tool https://github.com/int2str/jssyntaxtree for educational purposes, because it is the simplest and most intuitive tool I have found to create linguistic syntax trees. For a new model of visualizing syntax I've been working on, though, I need the tool to be able to create three different kinds of nodes instead of just the one it does now, which need to be graphically distinct (to my specifications), yet still simple to program for the user. I have NO IDEA how complex or not complex this project is.