My first websocket practice!

• Create the websocket server and wait for connections
• Forward the message to other clients when a message is received

• Establish a websocket with the server
• Check if the connection is successful
• Send messages to the server

• Basic node.js
• ws library
• Message forwarding techniques

• Basic jQuery grammar
• How to create websockets
• How to manipulate elements with jQuery statements

1. In html, id is case-sensitive!!!
2. To use jQuery, add <script src="https://ajax.aspnetcdn.com/ajax/jQuery/jquery-3.4.1.min.js"></script> (You may change the link to other CDNs) before other code.
3. What does $(function() {*}); do? The function inside is executed when the page is ready. (https://stackoverflow.com/questions/7642442/what-does-function-do)
4. I learned this from https://medium.com/@martin.sikora/node-js-websocket-simple-chat-tutorial-2def3a841b61
5. If the user is using mozilla, we should use its built-in websocket. To use the apporiate websocket, we can do it like this:

window.WebSocket = window.WebSocket || window.MozWebSocket;

6. To create the websocket:

var conn = new WebSocket("ws://" + location.hostname + ":8080");

7. You can use $(this) within an event handler for an element.
8. The websocket server should not forward the message to the client who sent the message. To do this:

wss.clients.forEach(function(client) {
    if (client !== ws && client.readyState === websocket.OPEN) {
        client.send(data);
    }
});