When a product is added or removed from a cart

<script>
var dataLayer  = window.dataLayer || [];
dataLayer.push({
  'event': 'addToCart',
  'ecommerce': {
    'currencyCode': 'EUR',
    'add': {
    'products': [{
        'name': 'iPhone 6',      //name or id required
        'id': 'ip22122',    //name or id required
        'price': '699.99',
        'brand': 'Apple',
        'category': 'phone',
        'variant': 'rose gold',
        'quantity': '1'       }]
    }
  }
});
</script>