Browser WebSocket

const API_KEY = 'YOUR_API_KEY'
const WSS_URL = 'wss://wss.finlight.me' // Use '/raw' path for raw articles

let ws = null
let pingInterval = null
let reconnectTimeout = null
let reconnectAttempt = 0

function connect(filters = {}) {
  const params = new URLSearchParams({
    apiKey: API_KEY,
    takeover: 'true',
    clientVersion: 'my-app/1.0',
  })
  const url = `${WSS_URL}?${params}`

  ws = new WebSocket(url)

  ws.onopen = () => {
    console.log('Connected')
    reconnectAttempt = 0

    // Send subscription with filters
    ws.send(JSON.stringify({
      clientNonce: crypto.randomUUID(),
      query: filters.query || '',
      language: filters.language || 'en',
      sources: filters.sources || [],
      tickers: filters.tickers || [],
      countries: filters.countries || [],
    }))

    // Start heartbeat
    pingInterval = setInterval(() => {
      if (ws.readyState === WebSocket.OPEN) {
        ws.send(JSON.stringify({
          action: 'ping',
          t: Date.now(),
        }))
      }
    }, 25000)
  }

  ws.onmessage = (event) => {
    const msg = JSON.parse(event.data)

    switch (msg.action) {
      case 'admit':
        console.log('Admitted, lease:', msg.leaseId)
        break
      case 'sendArticle':
        console.log('Article:', msg.data.title)
        // Handle the article here
        break
      case 'pong':
        break // Heartbeat OK
      case 'preempted':
        console.warn('Connection replaced')
        break
      case 'error':
        console.error('Server error:', msg.data || msg.error)
        break
    }
  }

  ws.onclose = (event) => {
    clearInterval(pingInterval)

    // Don't reconnect on policy violations
    if (event.code === 1008 || event.code === 4002) {
      console.error('Connection blocked')
      return
    }

    // Exponential backoff reconnect
    const delay = Math.min(500 * 2 ** reconnectAttempt, 10000)
    reconnectAttempt++
    console.log(`Reconnecting in ${delay}ms...`)
    reconnectTimeout = setTimeout(() => connect(filters), delay)
  }

  ws.onerror = () => console.error('WebSocket error')
}

function disconnect() {
  clearInterval(pingInterval)
  clearTimeout(reconnectTimeout)
  if (ws) ws.close(1000)
}

// Usage
connect({ query: 'Nvidia', language: 'en', countries: ['US'] })