additional_checkout_script.html

<script type="text/javascript">
var buildProductFieldObject = function(object, quantity) {
    var product = {};
    if (object.title) {
      product.name = object.title;
    }
    if (object.id) {
      product.id = object.id;
    }
    if (object.price) {
      product.price = parseFloat(object.price) / 100;
    }
    if (object.vendor) {
      product.brand = object.vendor;
    }
    if (quantity) {
      product.quantity = quantity;
    }
    return product;
  };
if (typeof Shopify.Checkout !== 'undefined' && typeof Shopify.checkout !== 'undefined' && Shopify.Checkout.page === 'thank_you') {
  var orderId = Shopify.checkout.order_id;
  var totalPrice = Shopify.checkout.total_price;
  var totalTax = Shopify.checkout.total_tax;
  var totalShipping = Shopify.checkout.shipping_rate.price || 0;
  var coupon = Shopify.checkout.discount;

  var orderId = Shopify.checkout.order_id;
      var totalPrice = Shopify.checkout.total_price;
      var totalTax = Shopify.checkout.total_tax;
      var totalShipping = Shopify.checkout.shipping_rate.price || 0;
      var coupon = Shopify.checkout.discount;

      var orderProducts = [];
      for (var k = 0; k < Shopify.checkout.line_items.length; k++) {
        var orderProduct = Shopify.checkout.line_items[k];
        orderProducts.push(
          buildProductFieldObject(orderProduct)
        );
      }

      // Call GTM to tell event checkout
      var thankyouEvent = {
        event: 'purchase',
        ecommerce: {
          purchase: {
            actionField: {
              id: orderId,
              revenue: totalPrice,
              tax: totalTax,
              shipping: totalShipping,
              coupon: coupon
            },
            products: orderProducts
          }
        }
      };

window.dataLayer = window.dataLayer || [];
    window.dataLayer.push(thankyouEvent);
}
</script>
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