Alert on line move

Detect when a quote moves more than n% from its previous value. Useful for early-line tracking, sharp-action signals, or simply “tell me when the Lakers spread moves a half-point”.

Minimal version

import { createClient, type SelectionId } from 'realtimeodds'

const client = createClient({
  url: 'wss://api.realtimeodds.xyz',
  apiKey: process.env.REALTIMEODDS_API_KEY!
})

const lastPrice = new Map<SelectionId, number>()
const THRESHOLD = 0.02  // alert on >2% move

client.on('odds:changed', ({ bookmaker, sportEventId, selectionId, quote }) => {
  const previous = lastPrice.get(selectionId)
  lastPrice.set(selectionId, quote.price)

  if (previous == null) return  // first sighting — no comparison
  const move = (quote.price - previous) / previous

  if (Math.abs(move) >= THRESHOLD) {
    const direction = move > 0 ? '↑' : '↓'
    console.log(
      `[ALERT] ${bookmaker} ${sportEventId} ${selectionId}: ${previous.toFixed(2)} → ${quote.price.toFixed(2)} (${direction} ${(move * 100).toFixed(1)}%)`
    )
  }
})

await client.connect()

Filter to a specific match

If you only care about one event, drop everything else early:

const watchedEventId = 'vmid:ps3838:1610547234'

client.on('odds:changed', payload => {
  if (payload.sportEventId !== watchedEventId) return
  // … threshold check as above
})

Filter to a specific market kind

Drop player props or only watch the moneyline by reading the parent market:

client.on('odds:changed', payload => {
  const ev = client.getSportEvent(payload.sportEventId)
  const market = ev?.getMarket(payload.marketId)
  if (market?.kind !== 'market:basketball_match.moneyline') return
  // … alert logic
})

Cooldown

Without throttling, a flickering market can fire dozens of alerts. Add a per-selection cooldown:

const lastAlertAt = new Map<SelectionId, number>()
const COOLDOWN_MS = 30_000

function shouldAlert(selectionId: SelectionId): boolean {
  const now = Date.now()
  const last = lastAlertAt.get(selectionId) ?? 0
  if (now - last < COOLDOWN_MS) return false
  lastAlertAt.set(selectionId, now)
  return true
}

Wrap the alert in if (shouldAlert(selectionId)) { … }.

Direction-only alerts

If you want to fire only when the line moves toward a specific team — say, Lakers shortening from +5 to +3:

import type { BasketballHandicap } from 'realtimeodds'

client.on('odds:changed', payload => {
  const ev = client.getSportEvent(payload.sportEventId)
  const market = ev?.getMarket(payload.marketId)
  if (market?.kind !== 'market:basketball_match.handicap') return

  const handicap = (market as BasketballHandicap).handicap
  const previous = lastHandicap.get(payload.marketId)
  lastHandicap.set(payload.marketId, handicap)

  if (previous != null && handicap > previous) {
    // line moved toward home team
  }
})

Send to Slack / Discord / email

Replace the console.log with a webhook call. Keep it out of the listener path — push the event onto a queue and drain asynchronously to avoid backpressure on the event loop:

const alertQueue: Alert[] = []

client.on('odds:changed', payload => {
  // … threshold/cooldown logic
  alertQueue.push({ ...payload, ts: Date.now() })
})

setInterval(async () => {
  const batch = alertQueue.splice(0)
  for (const alert of batch) {
    await fetch(SLACK_WEBHOOK, { method: 'POST', body: JSON.stringify({ text: format(alert) }) })
  }
}, 1000)

This keeps the listener fast — see Filtering & performance for more on this pattern.