tracker.init()

Initializes the tracker. Activates the event flush timer, mounts the overlay (if enabled), and emits the initial session:start event.

tracker.init(userIdFn?: () => string | null): void

Parameters

userIdFn (optional)

Type: () => string | null

A function that returns the current user ID. Called once at init time to set the initial user identity for the session.

• Return a string to identify the user.
• Return null to use an anonymous session-scoped ID.

// Anonymous
tracker.init()

// With user ID from localStorage
tracker.init(() => localStorage.getItem('userId'))

// With user ID from a global auth object
tracker.init(() => window.__auth?.userId ?? null)

// With user ID from a store (must be synchronous)
tracker.init(() => authStore.getState().userId)

Behavior

• Singleton: safe to call multiple times — subsequent calls are no-ops. The tracker is initialized exactly once per page lifetime.
• Reuses pre-init client: if setupTrackers() was called first (which happens automatically via the injected setup script), init() reuses the same TrackerClient instance already holding the queued events. If called without a prior setupTrackers() (e.g. in a fully manual setup), a fresh client is created.
• Queue activation: calling init() activates the event flush timer. Events enqueued before init() (by the auto-trackers) are flushed on the first interval.

When Is It Called?

Automatic (autoInit: true, default)

The plugin injects an auto-init script that calls tracker.init(userIdFn) automatically. You don't need to call it yourself.

The userIdFn used is the one configured in track.userId:

// vite.config.ts
trackerPlugin({
  appId: 'my-app',
  track: {
    userId: () => localStorage.getItem('userId'),
  },
})
// ↑ This serializes the function and injects:
// tracker.init(() => localStorage.getItem('userId'))

Manual (autoInit: false)

When autoInit: false, you must call tracker.init() yourself:

// vite.config.ts
trackerPlugin({
  appId: 'my-app',
  autoInit: false,
})

// In your app
import { tracker } from '@ndriadev/vite-plugin-monitor/client'
tracker.init(() => getAuthStore().userId ?? null)

Examples

After Cookie Consent

import { tracker } from '@ndriadev/vite-plugin-monitor/client'

async function bootstrap() {
  const consent = await showCookieConsentBanner()

  if (consent.analytics) {
    tracker.init(() => localStorage.getItem('userId'))
  }
}

After Authentication

import { tracker } from '@ndriadev/vite-plugin-monitor/client'

authService.onLogin((user) => {
  tracker.init(() => user.id)
})

Conditional by Environment

import { tracker } from '@ndriadev/vite-plugin-monitor/client'

if (import.meta.env.VITE_ENABLE_ANALYTICS === 'true') {
  tracker.init(() => window.__auth?.id ?? null)
}

Session Start Event

When tracker.init() is called, a session:start event is automatically emitted:

{
  "type":      "session",
  "level":     "info",
  "userId":    "user_123",
  "payload": {
    "action":  "start",
    "trigger": "init"
  }
}

Note: userId is part of the event envelope (the TrackerEvent wrapper), not the SessionPayload. The payload for an init trigger carries only action and trigger.