[SigmundA]

Server side Blazor is pretty interesting, renders everything in type safe .Net on the server then uses websockets to update dom and bridge javascript. Supports client side webassembly execution model too but not stable.

Not exactly lightweight and I guess still a SPA approach but pretty state of the art in server side rendering I would say:

https://dotnet.microsoft.com/apps/aspnet/web-apps/blazor

[nocubicles]

Server Side Blazor looks very interesting and I've been meaning to try it out.

But do you have experience with it to answer the question OP had?

I.e How does it work with Server Side Blazor:

  - Showing/hiding UI elements
  - Possible values of one dropdown depending on the value selected in some other dropdown
  - Copying billing address to shipping address
  - Value of a radio button showing/hiding some form fields
  - (I hope you get the point...)

[SigmundA]

I don't have any experience with it I also keep wanting to try it it out. However the examples in the docs make it pretty clear how to accomplish those things, you have events that trigger a cshtml rerender to update the dom with c# code.

The example on the main page increments a counter using the @onclick event of a button, the @ denotes a server event.

If you ever used webforms back in the day it has some similarities.