It uses DOM, yes. And you should be able to run D3.js in it.

Some browser compatibility layer will be required though.

The plan for Sciter.JS is to provide minimal DOM implementation to keep it lightweight.

For example there is no document.getElementsByTagName method but there is document.querySelectorAll.

So if that exact method is needed anyone can add:

    Document.prototype.getElementsByTagName = function(tag) {
      return  this.querySelectorAll(tag);
    }

That's the idea of Sciter.JS: engine with core functionality that can be configured to run browser and electron applications, just a matter of adequate compatibility layer.