shopify-modulo

shopify.liquid

{% for product in collection.products %}
  {% capture everyThird %}{{ forloop.index | modulo: 3 }}{% endcapture %}
  {% capture everyOnePastThird %}{{ forloop.index0 | modulo: 3 }}{% endcapture %}

  {% if forloop.first == true or everyOnePastThird == '0' %}
    <div class="row">
  {% endif %}
    {% include 'product-catalog-item' %}

  {% if forloop.last == true or everyThird == '0' %}
    </div>
  {% endif %}
{% endfor %}