Socket.IO 클라 (JavaScript)

import { io } from 'socket.io-client';

const socket = io('https://api.example.com', {
  auth: { token: 'jwt-here' },
  reconnection: true,
  reconnectionDelay: 1_000,
  reconnectionDelayMax: 30_000,
  randomizationFactor: 0.5,
});

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

socket.on('disconnect', (reason) => {
  console.log('disconnected:', reason);
  // Common reasons: 'io server disconnect', 'io client disconnect',
  //                 'ping timeout', 'transport close', 'transport error'
});

socket.on('chat:message', (data) => {
  console.log(`${data.from}: ${data.text}`);
});

// Send + acknowledge with callback
socket.emit('chat:message', { room: 'general', text: 'hi' }, (ack) => {
  console.log('server ack:', ack);
});

// Send + acknowledge with promise (v4.6+)
const ack = await socket.emitWithAck('chat:message', {
  room: 'general', text: 'hi',
});