Socket.IO connect and disconnect handlers

In the <script> section of the file, on line (2), we create an instance of the io() class from the socket.io JavaScript library and assign it to the socket variable:

    var socket = io();                         // (2)

    socket.on('connect', function() {          // (3)
        console.log("Connected to Server");
        $("#connected").html("Yes");
    });

    socket.on('disconnect', function() {       // (4)
        console.log("Disconnected from the Server");
        $("#connected").html("No");
    });

On line (3), with socket.on('connect', ...), we register a connect event listener. This handler is called every time our web page client connects successfully to our Python server. This is the client-side equivalent of the Python server's on connect handler we defined with @socketio.on('connect').

On...