Is there are web framework that allows creating of custom Web UI designers that can be embedded into a webpage/webapp?
What I am looking for is to create a web UI that allows users to edit the UI in a drag and drop style editor. It should be possible to select some widgets (like these: http://scaffy.railsware.com/futurico/#pagination) and to select a data source (will be provided by back-end, nodejs).
Background: I am not a web designer and have no previous web experience. I just want to know if it possible to create what I am looking for and how much effort it would be. My background is in embedded Linux development and I would like to create an easy way for people to create machines with single board computers. The embedded stuff is pretty much complete and I am exploring ways to create nice and user editable user interfaces.
I think what you want is possible.
However... as far I know nothing exists which will do exactly what you require.
There are thousands of UI widgets on the Web to choose from but you would need a custom built backend cms developed especially for your needs
There plenty of Web agencies who could provide a bespoke solution. They could also assist with updates and adding new widgets.
So it can be done (and may encounter some browser incompatability issues), but you'll just have to be prepared to spend money.