27. What is WebSocket and what makes it better (or worse) from HTTP?

WebSocket is a network communication protocol that enables real-time, bidirectional communication between a client and a server over a single TCP connection. WebSocket is ideal for applications that require rapid data exchange, such as chat applications, online games, or trading platforms.

Advantages of WebSocket compared to HTTP:

1. Bidirectional communication: Allows the server to send data to the client without the client initiating a request.
2. Low latency: Once the connection is established, data can be transmitted with minimal delay, which is crucial for real-time applications.
3. Efficiency: WebSocket uses fewer network resources than HTTP because it does not require opening and closing connections for each request.
4. Persistent connection: The connection remains open, enabling continuous data exchange between the client and server.

Example of using WebSocket in JavaScript:

const socket = new WebSocket('ws://example.com/socket');

socket.onopen = function(event) {
  console.log('WebSocket is open now.');
};

socket.onmessage = function(event) {
  console.log('Received data from server: ' + event.data);
};

socket.onclose = function(event) {
  console.log('WebSocket is closed now.');
};

socket.onerror = function(error) {
  console.error('WebSocket error: ' + error);
};

WebSocket is a powerful tool for applications requiring immediate data exchange and bidirectional communication.