At my previous job I worked at a whole UI framework (server side) based on XSLT transformations. We built kind of abstraction layer on top of ExtJS,HighCharts a

At my previous job I worked at a whole UI framework (server side) based on XSLT transformations. We built kind of abstraction layer on top of ExtJS,HighCharts and some 3D rendering lib at that time. It was hell to debug anything in there because the output was HTML sprinkled with JavaScript and it was not always easy to identify what part of XML and XSLT was responsible for given part of output. It was quite successfully used in one internal ERP mashup app that sucked data out of some SAP system. Learning XSLT actually helped me understand C++ templates (big aha moment). So we had this XSLT monster crunching on XML files but what we really needed was JSX which probably wasn't a thing until few years into the project.