client2.html

<script src="./assets/js/jquery-3.2.1.min.js"></script>
<script src="./assets/js/reconnecting-websocket.min.js"></script>
<script>
  $(document).ready(function(){    
    var url = "ws://nodewebsocketserver.herokuapp.com";
    // var url = "ws://localhost:3000";
    socket = new ReconnectingWebSocket(url);
    socket.onmessage = function (msg) {          
        var message = JSON.parse(msg.data);
        $('#command').text("time: " + message.time + "  ->  action: " + message.action + ", command: " + message.command + ", url: " + message.url);
        console.log(message);
    };
    socket.onopen = function () {
        var message = {};
        message.action = "register_client";  
        message.nick_name = "Test_Client2";
        message.master = false;             
        socket.send(JSON.stringify(message));
    };
  });
</script>
<ul id="notes"></ul>
<div id="command"></div>
<div id="newNote">Create a new note</div>
<input type = "button" style = "width: 200px; height: 140px;" value = "Send">