Events

Built-in and custom events

Built-in Events

connect

Emitted when connection established.

socket.on('connect', () => {
  console.log('Connected:', socket.id);
});

disconnect

Emitted when connection lost.

socket.on('disconnect', () => {
  console.log('Disconnected');
});

connect_error

Emitted on connection failure.

socket.on('connect_error', (error) => {
  console.error('Connection error:', error);
});

error

Emitted on socket errors.

socket.on('error', (error) => {
  console.error('Socket error:', error);
});

Custom Events

Define custom events for application logic.

Server Side

server.on('connection', (socket) => {
  socket.on('chat-message', (data) => {
    console.log('Chat message:', data);
  });
});

Client Side

socket.on('chat-message', (data) => {
  displayMessage(data);
});

socket.emit('chat-message', {
  text: 'Hello',
  user: 'Alice'
});

Event Naming

Best practices:

• Use kebab-case: 'user-joined'
• Be descriptive: 'message-received'
• Namespace if needed: 'chat:message'