Can I make web interface for hardware events?

Not quite sure if I'm helping here, but in answer to your previous questions:

Yes, you can do a loop - just setInterval(myLoopFunction, time_in_ms_to_call_fn).

But you probably shouldn't need that - even though it is the obvious thing to do coming from Arduino.

Espruino is event based, so once you've set up a webserver with a callback function, that function will be called back when a web page is requested. If you set up a KeyPad, that KeyPad's callback function will get called when a key is pressed too.

Both things will work together just fine without you having to worry -no loop needed.