gaEcommerceTracking.js

<script>
      

      // more documentation : https://developers.google.com/analytics/devguides/collection/analyticsjs/ecommerce 

      ga('require', 'ecommerce'); // You have to require the ecommerce Addon

      ga('ecommerce:addTransaction', {
        'id': '{{orderId}}',                     // Transaction ID. Required.
        'revenue': '{{orderToal}}',               // Grand Total.
        'currency': 'EUR' 
        });
  	
     // We add each item to the order 
     {{#each items}}
     
      ga('ecommerce:addItem', {
        'id': '{{orderId}}',                // Transaction ID. Required.
        'name': '{{items.name}}',          // Product name. Required.
        'sku': '{{items.sku}}',           // SKU/code.
        'price': '{{items.price}}',       // Unit price.
        'quantity': '{{items.quantity}}' // Quantity.
      });
       
    {{/each}}
	
    ga('ecommerce:send'); // send the data to GA
    
    ga('ecommerce:clear'); // clear 
		  
</script>

gtmEcommerce.js

<script>
window.dataLayer = window.dataLayer || []
dataLayer.push({
   'transactionId': '1234', // the transaction id
   'transactionTotal': 38.26, // the transaction total
   'transactionTCurrency':'EUR', // the transaction currency
   'transactionProducts': [
     // Put in an array of object all the products of the order
     {
       'sku': 'DD44',
       'name': 'T-shirt',
       'category': 'Vêtement',
       'price': 11.99,
       'quantity': 1
   },{
       'sku': 'AA1243544',
       'name': 'Chaussettes',
       'category': 'Vêtement',
       'price': 9.99,
       'quantity': 2
   }
   ]
});
</script>