nodejs reactor implementation

I am trying to get idea how nodejs's 'Reactor pattern' works. But unfortunately I can't find any real implementation of it.

I want to understand how the tick (yep, tick of event loop) works. So, the basic idea is to debug this 'Reactor'. For example: when I run node app.js what exactly happens? What kind of events will be in the event loop, event demultiplexer, event queue etc. How they interact with each other? Or when we create and I/O request. Or maybe then, inside of one I/O request we create another one.

Hope you get the basic idea what I am trying to get to know.

Maybe you have some kind of js implementation of node's Reator where I can put some console.log()'s.

I was trying to google this, but unfortunately I always get only basic idea how it works. Or a lot of reactors the are not basically 'node's reactors'.

Could anyone help me with it?

Thanks