[mstijak]

I would like to share my view as of an author of a JS UI framework. It largely depends on the project, but sometimes it can be very difficult to integrate many libraries to play nicely together. To build an admin web application with some data entry, a developer would need a set of standard widgets like inputs and menus, a nice data table implementation, form validation engine, a router and a state management library. For more serious applications charts may also be needed, multi-lingual support and some advanced widgets like maps, html editor, calendar, or diagrams. If each of those is a separate library with separate rules for styling, state management, selection, number and date formatting, context menus, tooltips, the project quickly becomes very very complex. If all things are integrated into a framework you get a sane development experience. There are always some sacrifices and some features may be missing, but frameworks usually cover 80-90% of all requirements. The problem is that requirements change and frameworks usually have hard time to catch up and preserve backward compatibility.