Good point on the complexity of today web apps. I'm not really into web front-end and my comment was more about native frontend development, where you need to add/remove things from screen, run animations, you know, those sort of things that are inherently non-functional. Sorry for not being clearer.

It's ok! :)

So, if we only want to call a couple of animations and submit a form, I agree that a small script with three jQuery-style functions can do the job.

But that's rarely the case nowadays, in my experience. Almost every frontend project I came across professionally became a full application at some point.

There's the need of dealing with concurrent user interactions, online data requests to the server, non-traditional form behaviors, different routes...

Here is an example of something small that can benefit from F# sharing:

http://banashek.com/posts/20170204-a-brief-peek-at-universal...

Sharing types, validators, etc mean that the api communication is type-safe.

Really good, amazing example