Select first variant with stock

select_variant_with_stock.liquid

$(document).ready(function() {
    var parentId;
    var parentOptionCounter = 0;
    
    $.each($(".prod-options option"), function( index, option ) {
  		var stock = $(option).data("variant-stock");
      if(index == 0 || parentId !== $(option).parent().attr('id')){
        parentId = $(option).parent().attr('id');
        parentOptionCounter = 0;
      }
		  if(stock != '0' && parentOptionCounter > 0){ 
        $(option).prop('selected', true).trigger('change'); // selecting the first non-stock zero option.
        return false;
      }
      
      parentOptionCounter++;
		});         
  });