Tracking Events

Once Analytics automatically tracks pageviews and clicks. You can also track custom events to measure specific actions.

Automatic tracking

The tracking script automatically captures:

Page views — Every page load and SPA navigation
Click events — Clicks on links, buttons, and form inputs
Session data — Visit duration and page flow
Technical data — Browser, OS, device type, country

No configuration required for basic tracking.

Custom events

Track any action using the dataLayer (same format as Google Tag Manager):

javascript

// Basic event
dataLayer.push({ event: 'signup' });

// Event with properties
dataLayer.push({
  event: 'purchase',
  value: 99.99,
  currency: 'USD',
  product: 'Pro Plan'
});

Common events to track

javascript

// Newsletter signup
dataLayer.push({ event: 'newsletter_signup' });

// Form submission
dataLayer.push({ event: 'contact_form_submit' });

// Video play
dataLayer.push({ event: 'video_play', video_id: 'intro' });

// Download
dataLayer.push({ event: 'download', file: 'whitepaper.pdf' });

// Add to cart
dataLayer.push({
  event: 'add_to_cart',
  product_id: 'SKU123',
  price: 49.99
});

Event properties

Any properties you include with the event are stored in the event_data field as JSON:

javascript

dataLayer.push({
  event: 'purchase',
  order_id: '12345',
  total: 149.99,
  items: 3
});

These properties can be queried directly from your D1 database.

Click tracking

Clicks are automatically tracked on:

Links (<a>) — Both internal and external
Buttons (<button>) — Standard buttons
Form inputs (<input>) — Buttons and submit inputs
Role buttons — Elements with role="button"

Click data captured:

Field	Description
Element ID	The `id` attribute if present
Element text	Button/link text (max 50 chars)
Href	Link destination
Tag	HTML tag name

Outbound vs Inbound links

Outbound — Links starting with http going to other domains
Inbound — Relative paths and same-domain links

SPA support

For single-page applications (React, Vue, Next.js, etc.), Once Analytics automatically tracks navigation by intercepting:

history.pushState()
history.replaceState()
popstate events (browser back/forward)

No additional configuration needed for most SPAs.

Google Tag Manager

If you're already using GTM, Once Analytics captures all dataLayer.push() events automatically.

Tip: You can run Google Analytics and Once Analytics side-by-side. Both read from the same dataLayer without conflicts.

Filtered GTM events

These GTM system events are automatically filtered out:

gtm.js, gtm.dom, gtm.load
gtm.click, gtm.linkClick
gtm.formSubmit, gtm.scrollDepth
Events starting with gtm.

UTM parameters

UTM parameters are automatically captured from URLs:

Parameter	Description
`utm_source`	Traffic source (google, newsletter)
`utm_medium`	Marketing medium (cpc, email, social)
`utm_campaign`	Campaign name
`utm_term`	Paid search keywords
`utm_content`	Ad/link variant

Example URL:

https://yoursite.com/?utm_source=twitter&utm_medium=social&utm_campaign=launch

View UTM data in Dashboard → Campaigns.

Data sanitization

For privacy and security, these query parameters are automatically redacted:

Authentication: session_id, token, access_token, jwt, code

Personal data: user_id, email, username, phone

Security: password, secret, csrf_token, api_key

Payment: card, cvv, account_number

Ad tracking: fbclid, gclid, msclkid

Values are replaced with REDACTED before storage.

Questions? Email hello@onceanalytics.com