Global properties & opt-out

Attach properties to every event, transform events before they're sent, and respect user consent — all server-side.

#Global (super) properties

register() adds properties merged into every subsequent event at the lowest precedence (per-event properties win on a key collision). unregister() removes one.

vtilt.register({ app_version: '2.1.0', environment: 'production' })
vtilt.unregister('app_version')

You can also set them once at construction:

const vtilt = new VTiltNode(token, {
  globalProperties: { service: 'checkout-api' },
})

#Person properties

Set properties on the person record without sending a custom event:

vtilt.setPersonProperties('user_123', { plan: 'pro' }) // $set on every event
vtilt.setPersonPropertiesOnce('user_123', { signup_source: 'docs' }) // $set_once

#before_send

Pass a hook (or array of hooks) to mutate events or drop them. Return the event to keep it, or null to drop it. Multiple hooks run in order; the first null drops the event.

const vtilt = new VTiltNode(token, {
  before_send: event => {
    if (event.event === 'debug_event') return null // drop
    event.payload.region = process.env.REGION
    return event
  },
})

#Opt-out (GDPR)

vtilt.optOut() // drop all events until opted back in
vtilt.optIn()
vtilt.isOptedOut() // boolean

disable() / enable() are a separate kill switch (e.g. to turn the SDK off entirely in a given environment).

#Lifecycle listeners

Subscribe to delivery events. on() returns an unsubscribe function.

const off = vtilt.on('error', err => logger.error('vtilt flush failed', err))
vtilt.on('flush', batch => metrics.increment('vtilt.events.sent', batch.length))