So, how does this work?

Is this just a DOM implementation that writes out the serialised form, or does it write our JavaScript to render whatever you've set, client side?

It's the latter. It establishes a WebSocket connection and issues JavaScript commands to execute from the server. This connection remains persistently to allow bi-directional communication between client and server.

This occurs "behind the scenes", the developer will rarely need to think about it.

This is my project, would love feedback, not just on the idea itself - but also how I go about explaining it on the site.