If you want to track which marketing channels are actually generating bookings and revenue in Google Analytics 4, you can connect your ReservationKey booking engine to GA4 ecommerce tracking using ReservationKey's built-in data layer.

This guide walks through a working setup that supports:

• Revenue attribution in GA4
• Cross-domain tracking between your website and ReservationKey booking pages
• Ecommerce purchase events
• Tracking by room, cottage, cabin, or unit
• Attribution from sources like Facebook, Instagram, TripAdvisor, Google Search, and more

Special thanks to ReservationKey customer Paul from Kauai Cottages for helping test and refine this approach.

How the Tracking Works

The setup uses two pieces:

• A GA4 tracking script loaded on every ReservationKey booking page
• A purchase event script that runs only on the final confirmation page

The purchase event reads booking details from:

window.reservationData

This object contains reservation information such as:

• Reservation ID
• Payment amount
• Taxes
• Room/unit ID
• Check-in/check-out dates
• Guest count
• Page alias

This data is available reliably on the final confirmation page. See this blog post for complete data layer specifications.

Important: Do Not Use ReservationKey Merge Codes for GA4 Ecommerce Tracking

Some users initially try using ReservationKey email merge codes such as:

{{CONFIRMNUM}}
{{TOTALPRICE}}
{{ROOMNAME}}

However, these merge codes are designed for ReservationKey email templates, not JavaScript ecommerce tracking.

Instead, always use:

window.reservationData

Step 1 - Add the GA4 Script to Code on Every Page

In ReservationKey, go to:

Website -> Reservation Pages -> Edit -> Settings -> Settings 2

Paste this into:

Code on EVERY page

<!-- Google tag (gtag.js) -->
<script async src="https://www.googletagmanager.com/gtag/js?id=G-XXXXXXXXXX"></script>

<script>
window.dataLayer = window.dataLayer || [];

function gtag(){
  dataLayer.push(arguments);
}

gtag('js', new Date());

gtag('config', 'G-XXXXXXXXXX', {
  'linker': {
    'domains': [
      'yourwebsite.com',
      'v2.reservationkey.com'
    ],
    'accept_incoming': true
  }
});
</script>

Replace:

• G-XXXXXXXXXX with your GA4 Measurement ID
• yourwebsite.com with your own domain name

Step 2 - Enable Cross-Domain Tracking in GA4

Inside Google Analytics 4, go to:

Admin -> Data Streams -> Your Web Stream

Then:

Configure tag settings -> Configure your domains

Add:

• yourwebsite.com
• v2.reservationkey.com

This allows GA4 to preserve the original traffic source when visitors move between your website and ReservationKey booking pages.

Without this step, bookings may appear as:

referral / v2.reservationkey.com

instead of the original source, such as:

• Facebook
• Google organic
• Instagram
• TripAdvisor
• Email campaigns

Step 3 - Add the Purchase Tracking Script

In ReservationKey, go to:

Website -> Reservation Pages -> Edit -> Settings -> Settings 2

Paste this into:

Code ONLY on final confirmation page

Example GA4 Purchase Tracking Script

This example tracks:

• Transaction ID
• Revenue
• Taxes
• Unit name
• Unit ID
• Ecommerce purchase event

<script>
/* ReservationKey GA4 Purchase Tracking */
(function(){

  if(window._rkPurchaseFired) return;

  window.dataLayer = window.dataLayer || [];

  function gtag(){
    dataLayer.push(arguments);
  }

  var rd = window.reservationData;

  if(!rd || !rd.id_reservation){
    console.log("[RK] No reservationData");
    return;
  }

  var txnId = rd.id_reservation;
  var value = parseFloat(rd.payments) || 0;
  var tax = parseFloat(rd.taxes) || 0;
  var roomPrice = parseFloat(rd.total_room_price) || 0;

  /* Map ReservationKey room IDs to names; ID numbers are in the bottom right corner room settings pages */
  var unitMap = {
    "3099":"Ohana",
    "3101":"River",
    "3102":"Garden"
  };

  function resolveRoom(){
    var id = String(
      rd.id_room ||
      rd.idRoom ||
      rd.id_unit ||
      ""
    );
    return unitMap[id] || rd.page_alias || "Direct Booking";
  }

  function fire(){
    if(window._rkPurchaseFired) return;
    window._rkPurchaseFired = true;
    var itemName = resolveRoom();
    gtag("event", "purchase", {
      transaction_id: txnId,
      value: value,
      currency: "USD",
      tax: tax,
      items: [{
        item_id: String(rd.id_room || txnId),
        item_name: itemName,
        item_category: "rental",
        price: roomPrice,
        quantity: 1
      }]
    });
    console.log("[RK PURCHASE]", {
      txnId: txnId,
      value: value,
      room: itemName
    });
  }
  fire();
})();
</script>

Understanding window.reservationData

The ReservationKey booking engine exposes reservation information through:

window.reservationData

Some useful fields include:

You can inspect this object in your browser console:

console.log(window.reservationData)

Testing Your Setup

After placing a test booking:

1. Open Browser Developer Tools.
2. Check the console for messages like [RK PURCHASE].
3. In GA4, go to Reports -> Realtime.

You should see:

• A purchase event
• Revenue values
• Transaction IDs
• Item names

Recommended Approach

For most ReservationKey customers, the best setup is:

• Use GA4 with cross-domain tracking
• Use window.reservationData
• Track purchases using ecommerce events
• Map your room IDs to readable unit names

This gives you much better visibility into:

• Which marketing channels generate bookings
• Revenue attribution
• Conversion tracking
• Return on ad spend