SocketZone.com Internet Socket | Websocket Information Blog
Are you looking to learn about Javascript websocket example? In today’s world, websockets have become a popular way of enabling real-time communication between web applications. Websockets allow for two-way communication between the client and the server, making it an excellent choice for building chat applications, multiplayer games, and other real-time applications. In this article, we will explore what websockets are, how they work, and provide some examples of how to use websockets in Javascript.
What are websockets?
A websocket is a bi-directional communication protocol that enables real-time communication between a client and a server. It is a standard protocol that is implemented in most modern web browsers and servers. Websockets are used to send data between the client and the server in real-time, making it an ideal choice for web applications that require real-time updates.
Websockets are based on the TCP protocol, which is a reliable, connection-oriented protocol. Unlike HTTP, which is a request-response protocol, websockets enable real-time, bi-directional communication. When a websocket connection is established, both the client and the server can send data to each other whenever they want, without the need for a request from the client.
Websockets provide several advantages over other real-time communication technologies, such as AJAX, long polling, and server-sent events. Websockets are faster and more efficient than these technologies, and they enable real-time, two-way communication between the client and the server.
How do websockets work?
Websockets consist of two parts: the client-side API and the server-side API.
The client-side API provides a way for web developers to establish a websocket connection from the client to the server. The client-side API is built into modern web browsers, so there is no need for any additional plugins or software to be installed.
The server-side API provides a way for web developers to create a websocket server that can accept incoming websocket connections from clients. The server-side API is usually implemented using a server-side programming language such as Node.js, Python, or Java.
When a websocket connection is established, the client and server negotiate a protocol version and exchange a handshake. Once the handshake is complete, the client and server can start sending data to each other in real-time.
How to use websockets in Javascript?
Using websockets in Javascript is straightforward. The first step is to create a new websocket object using the WebSocket constructor:
var ws = new WebSocket('ws://localhost:8080');
This creates a new websocket object that is connected to the server at the specified URL. Once the websocket connection is established, you can listen for events using the onopen, onmessage, onerror, and onclose event handlers:
- onopen: This event is triggered when the websocket connection is established.
- onmessage: This event is triggered when the server sends a message to the client.
- onerror: This event is triggered when an error occurs with the websocket connection.
- onclose: This event is triggered when the websocket connection is closed.
Here is an example of how to use the onopen event handler:
ws.onopen = function() {console.log('Websocket connection established');};
And here is an example of how to use the onmessage event handler:
ws.onmessage = function(event) {console.log('Received message: ' + event.data);};
When the server sends a message to the client, the onmessage event handler is triggered, and the message is logged to the console.
WebSocket Example
Let’s look at a simple example of how to use websockets in Javascript. In this example, we will create a simple chat application that allows users to send messages to each other in real-time.
First, we need to create a websocket server using Node.js. Here is an example of how to create a websocket server using the ws module:
const WebSocket = require('ws');const wss = new WebSocket.Server({ port: 8080 });
wss.on('connection', function connection(ws) {console.log('Websocket connection established');
ws.on('message', function incoming(message) {console.log('Received message: %s', message);wss.clients.forEach(function each(client) {if (client !== ws && client.readyState === WebSocket.OPEN) {client.send(message);}});});});
This creates a new websocket server that listens on port 8080. When a new websocket connection is established, the server logs a message to the console. When the server receives a message from a client, it sends the message to all connected clients except the client that sent the message.
Next, we need to create a simple HTML page that contains a form for sending messages and a div for displaying messages:
<!DOCTYPE html><html><head><title>Websocket Example</title></head><body><form><input type="text" id="message" placeholder="Type a message"><button type="submit">Send</button></form><div id="messages"></div><script src="app.js"></script></body></html>
Finally, we need to create a Javascript file that handles sending and receiving messages:
var ws = new WebSocket('ws://localhost:8080');
ws.onopen = function() {console.log('Websocket connection established');};
ws.onmessage = function(event) {var messages = document.getElementById('messages');var message = document.createElement('div');message.innerHTML = event.data;messages.appendChild(message);};
document.querySelector('form').addEventListener('submit', function(event) {event.preventDefault();var input = document.getElementById('message');var message = input.value;input.value = '';ws.send(message);});
This creates a new websocket connection to the server and listens for incoming messages. When a message is received, it is displayed in the messages div. When the form is submitted, the message is sent to the server using the websocket connection.
Conclusion
In conclusion, websockets are an excellent choice for building real-time web applications. They enable efficient, bi-directional communication between the client and the server, making it possible to build applications such as chat applications, multiplayer games, and other real-time applications.
In this article, we have explored what websockets are, how they work, and provided some examples of how to use websockets in Javascript. We hope that this has been a helpful introduction to websockets and that you are now ready to start building your own real-time applications using websockets.
FAQs
- What is the difference between websockets and AJAX?
Websockets enable real-time, bi-directional communication between the client and the server, while AJAX is a request-response protocol that requires the client to make a request to the server and wait for a response. - Do all web browsers support websockets?
Most modern web browsers support websockets, including Chrome, Firefox, Safari, and Edge. - Can websockets be used for file transfers?
Yes, websockets can be used for file transfers, but it is not recommended for large files as it may impact performance. - What is the difference between websockets and long polling?
Long polling is a technique that involves making a request to the server and keeping the connection open until the server has new data to send. Websockets, on the other hand, keep the connection open and allow for real-time, bi-directional communication.
