This server js file and index.html are an example for WebSockets.
Click or tap screen and it will update all screens that opened this page
install Node.js
install Socket.io:
npm install socket.io
run
node server.js
visit
http://localhost:1337/index.html
or whatever domain you've set up - be sure to update index.html then:
var socket = io.connect('http://localhost:1337');