Benjamin Czegeny bczegeny

<script>
  $('#AddToCart').click(function() {
		$('#AddToCartForm').preventDefault();
    	if ( $('#serial-number').empty()) {
    	  	
          $('#serial-number').attr('placeholder','Enter your serial before adding to cart');
        } else {
          $('#AddToCartForm').submit();
 }

Create a snippet place this code in it

{% if template contains 'index' %}
  <script>
  {% for product_vendor in shop.vendors %}
    $('#vendor-filter').append($('<option>', {
      value: '{{ product_vendor | url_for_vendor }}',
      text: '{{ product_vendor }}'
    }));