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2. CRUD

✅ Mapping custom event names to CRUD actions

Each event is just a string, so you can define events like:

Action	Socket Event Name
Create	`create_item`
Read	`get_items`
Update	`update_item`
Delete	`delete_item`

1. Server-Side

const express = require('express');
const http = require('http');
const { Server } = require('socket.io');

const app = express();
const server = http.createServer(app);
const io = new Server(server);

// In-memory data store
let items = [];
let idCounter = 1;

io.on('connection', (socket) => {
  console.log('Client connected');

  // CREATE
  socket.on('create_item', (data) => {
    const item = { id: idCounter++, ...data };
    items.push(item);
    socket.emit('item_created', item);
  });

  // READ
  socket.on('get_items', () => {
    socket.emit('items_list', items);
  });

  // UPDATE
  socket.on('update_item', ({ id, ...updates }) => {
    let item = items.find(i => i.id === id);
    if (item) {
      Object.assign(item, updates);
      socket.emit('item_updated', item);
    } else {
      socket.emit('error', 'Item not found');
    }
  });

  // DELETE
  socket.on('delete_item', (id) => {
    items = items.filter(i => i.id !== id);
    socket.emit('item_deleted', id);
  });
});

server.listen(3000, () => {
  console.log('Server listening on http://localhost:3000');
});

2. 🧪 Client-Side

<script src="/socket.io/socket.io.js"></script>
<script>
  const socket = io();

  // CREATE
  socket.emit('create_item', { name: 'Apple', price: 3 });

  // READ
  socket.emit('get_items');
  socket.on('items_list', (items) => console.log('Items:', items));

  // UPDATE
  socket.emit('update_item', { id: 1, name: 'Green Apple' });

  // DELETE
  socket.emit('delete_item', 1);

  // Notifications
  socket.on('item_created', item => console.log('Created:', item));
  socket.on('item_updated', item => console.log('Updated:', item));
  socket.on('item_deleted', id => console.log('Deleted ID:', id));
</script>

🛡️ Notes

WebSockets are event-based, not resource-based.
There’s no standard CRUD pattern, so you define it yourself using clear naming.
If you need RESTful semantics, you can mix Socket.IO with regular HTTP routes too.