I'm trying to develop a service that works something like this:

• There is an app running listening for keypresses (even when in background).
• When a particular keypress happens I want my page to have it's content updated without reloading.
• So there is my site opened, I press for example "W" and let's say an element on the page becomes hidden instantly. Remember BOTH the app and the page are in the background/are unfocused.

I assume the page should be on local network and the app should be some kind of server, but correct me if I'm wrong.

I'm familiar with C#, JS, HTML and CSS. Understand the concept of Node.js but never really worked with it, same goes for ajax.

So how do I start? Which tools/knowledge do I need?

Thanks in advance!