Google Tag Manager examples for ecommerce tracking on GA4. More info: https://developers.google.com/analytics/devguides/collection/ga4/reference/events?client_type=gtm

ecommerce-ga4.js

// View item: It should be executed when the product detail is shown.
dataLayer.push({ ecommerce: null });
dataLayer.push({
  event: "view_item",
  ecommerce: {
    currency: "USD",
    value: 7.77,
    items: [
    {
      item_id: "SKU_12345",
      item_name: "Stan and Friends Tee",
      affiliation: "Google Merchandise Store",
      coupon: "SUMMER_FUN",
      discount: 2.22,
      index: 0,
      item_brand: "Google",
      item_category: "Apparel",
      item_category2: "Adult",
      item_category3: "Shirts",
      item_category4: "Crew",
      item_category5: "Short sleeve",
      item_list_id: "related_products",
      item_list_name: "Related Products",
      item_variant: "green",
      location_id: "ChIJIQBpAG2ahYAR_6128GcTUEo",
      price: 9.99,
      quantity: 1
    }
    ]
  }
});


// Add to cart: It should fire when the user click the buton with the intention to purchase the product.
dataLayer.push({ ecommerce: null }); 
dataLayer.push({
  event: "add_to_cart",
  ecommerce: {
    currency: "USD",
    value: 7.77,
    items: [
    {
      item_id: "SKU_12345",
      item_name: "Stan and Friends Tee",
      affiliation: "Google Merchandise Store",
      coupon: "SUMMER_FUN",
      discount: 2.22,
      index: 0,
      item_brand: "Google",
      item_category: "Apparel",
      item_category2: "Adult",
      item_category3: "Shirts",
      item_category4: "Crew",
      item_category5: "Short sleeve",
      item_list_id: "related_products",
      item_list_name: "Related Products",
      item_variant: "green",
      location_id: "ChIJIQBpAG2ahYAR_6128GcTUEo",
      price: 9.99,
      quantity: 1
    }
    ]
  }
});

// Begin checkout: It should fire as the first step in the checkout process (registered and logged or purchase as guest, if available)
dataLayer.push({ ecommerce: null });
dataLayer.push({
  event: "begin_checkout",
  ecommerce: {
    currency: "USD",
    value: 7.77,
    coupon: "SUMMER_FUN",
    items: [
    {
      item_id: "SKU_12345",
      item_name: "Stan and Friends Tee",
      affiliation: "Google Merchandise Store",
      coupon: "SUMMER_FUN",
      discount: 2.22,
      index: 0,
      item_brand: "Google",
      item_category: "Apparel",
      item_category2: "Adult",
      item_category3: "Shirts",
      item_category4: "Crew",
      item_category5: "Short sleeve",
      item_list_id: "related_products",
      item_list_name: "Related Products",
      item_variant: "green",
      location_id: "ChIJIQBpAG2ahYAR_6128GcTUEo",
      price: 9.99,
      quantity: 1
    }
    ]
  }
});

// Payment information submitted: It should fire when payment method information is entered by the user (optional: only if appropiate).
dataLayer.push({ ecommerce: null });
dataLayer.push({
  event: "add_payment_info",
  ecommerce: {
    currency: "USD",
    value: 7.77,
    coupon: "SUMMER_FUN",
    payment_type: "Credit Card",
    items: [
    {
      item_id: "SKU_12345",
      item_name: "Stan and Friends Tee",
      affiliation: "Google Merchandise Store",
      coupon: "SUMMER_FUN",
      discount: 2.22,
      index: 0,
      item_brand: "Google",
      item_category: "Apparel",
      item_category2: "Adult",
      item_category3: "Shirts",
      item_category4: "Crew",
      item_category5: "Short sleeve",
      item_list_id: "related_products",
      item_list_name: "Related Products",
      item_variant: "green",
      location_id: "ChIJIQBpAG2ahYAR_6128GcTUEo",
      price: 9.99,
      quantity: 1
    }
    ]
  }
});

// Purchase: It should fire at the confirmation page when user have completed the transatction and paid the purchase succefully.
dataLayer.push({ ecommerce: null });
dataLayer.push({
  event: "purchase",
  ecommerce: {
      transaction_id: "T_12345",
      value: 25.42,
      tax: 4.90,
      shipping: 5.99,
      currency: "USD",
      coupon: "SUMMER_SALE",
      items: [
       {
        item_id: "SKU_12345",
        item_name: "Stan and Friends Tee",
        affiliation: "Google Merchandise Store",
        coupon: "SUMMER_FUN",
        discount: 2.22,
        index: 0,
        item_brand: "Google",
        item_category: "Apparel",
        item_category2: "Adult",
        item_category3: "Shirts",
        item_category4: "Crew",
        item_category5: "Short sleeve",
        item_list_id: "related_products",
        item_list_name: "Related Products",
        item_variant: "green",
        location_id: "ChIJIQBpAG2ahYAR_6128GcTUEo",
        price: 9.99,
        quantity: 1
      },
      {
        item_id: "SKU_12346",
        item_name: "Google Grey Women's Tee",
        affiliation: "Google Merchandise Store",
        coupon: "SUMMER_FUN",
        discount: 3.33,
        index: 1,
        item_brand: "Google",
        item_category: "Apparel",
        item_category2: "Adult",
        item_category3: "Shirts",
        item_category4: "Crew",
        item_category5: "Short sleeve",
        item_list_id: "related_products",
        item_list_name: "Related Products",
        item_variant: "gray",
        location_id: "ChIJIQBpAG2ahYAR_6128GcTUEo",
        price: 20.99,
        promotion_id: "P_12345",
        promotion_name: "Summer Sale",
        quantity: 1
      }]
  }
});