sse.js

import { SSE } from 'sse.js'; const SSE_SERVER_URL = process.env.SSE_SERVER_URL ?? 'http://localhost:3000/events'; const AUTH_TOKEN = process.env.AUTH_TOKEN ?? 'your-secret-token'; interface MyEventData { message: string; timestamp: number; } async function connectToSSE() { const source = new SSE(SSE_SERVER_URL, { headers: { 'Authorization': `Bearer ${AUTH_TOKEN}`, 'Accept': 'text/event-stream', }, method: 'POST', payload: JSON.stringify({ initialData: 'client-hello' }), autoReconnect: true, reconnectDelay: 5000, maxRetries: 5, useLastEventId: true, // Recommended for resuming streams start: false, // Don't start streaming immediately }); source.addEventListener('open', (event: Event) => { const openEvent = event as Event & { responseCode?: number; headers?: Record<string, string[]> }; console.log(`SSE connection opened. HTTP Status: ${openEvent.responseCode}`); if (openEvent.headers) { console.log('Response Headers:', openEvent.headers); } }); source.addEventListener('message', (event: MessageEvent) => { try { const payload: MyEventData = JSON.parse(event.data); console.log(`Received event (id: ${event.lastEventId}):`, payload.message, `at ${new Date(payload.timestamp).toLocaleTimeString()}`); } catch (e) { console.error('Failed to parse event data:', e, event.data); } }); source.addEventListener('error', (event: Event) => { const errorEvent = event as Event & { responseCode?: number; message?: string }; console.error(`SSE connection error. HTTP Status: ${errorEvent.responseCode}, Message: ${errorEvent.message}`); if (source.autoReconnect && source.retryCount < (source.maxRetries ?? Infinity)) { console.log(`Attempting to reconnect in ${source.reconnectDelay}ms (attempt ${source.retryCount + 1}/${source.maxRetries ?? '∞'})...`); } else if (source.autoReconnect && source.maxRetries && source.retryCount >= source.maxRetries) { console.log('Max reconnection retries reached. Connection permanently closed.'); } else { console.log('Connection closed or not configured for auto-reconnect.'); } }); source.addEventListener('abort', () => { console.log('SSE connection aborted by client.'); }); // Manually start the stream after setting up listeners console.log('Starting SSE stream...'); source.stream(); // Example of closing the connection after some time setTimeout(() => { console.log('Closing SSE connection after 60 seconds...'); source.close(); }, 60000); } connectToSSE();