Detecting an html button click with node.js?
you are mixing up two different things, the data event in node which you are talking of is triggered because a network connection is established when you point the browser to your website, data is received and sent from the client to the server and back.
this has nothing to do with clientside ui events, for example a click event on a button.
if you want node to recognize a click on your button you have to send something to the server, you can either use a form, issue an ajax request or use websockets.
for ajax requests with jquery : jquery $.ajax documentation
a popular websockets implementation for node.js is socket.io