Validate Factura / Boleta presence for Jumpseller Checkout (for Invoicing Systems integration in Chile).

factura_boleta_validator.liquid

<script type="text/javascript">
  // On the Admin Panel Configuration: https://www.evernote.com/l/APbc8GhuD4VCBam1eRbZb_M0Jr-wKdQqTVQ add the Custom Fields:
  // Select List (Boleta o Factura) with the options: "Boleta Electrónica" and "Factura Electrónica"
  // Input Fields: "Razón Social" and "Giro"
  // Store Theme Checkout Form: https://www.evernote.com/l/APYKFPLISu9GpJihPufTIFUiLT7bhyUgWBU 
  // use this on the Template: "Payment/Checkout" with {% include 'factura_boleta_validator' %}
  $(document).ready(function(){
    //Chile Tax ID Verifier
    $("#order_shipping_address_taxid").attr("pattern", "[0-9]{7,8}-[0-9Kk]{1}"); // with . and . [0-9]{1,2}.[0-9]{3}.[0-9]{3}-[0-9Kk]{1}
    $("#order_shipping_address_taxid").attr("placeholder", "ej. 12345678-5");
    $("#order_shipping_address_taxid").attr("title", "ej. 12345678-5");
  
  $("#checkout").on("submit", function(){
    var option = $("#order_other_boleta_o_factura option:selected").val();
      if(option == 'Factura Electrónica'){
        if(!$('#order_other_razon_social').val() || !$('#order_other_giro').val()){
          alert('Razón Social o Giro no presente.');
          return false;
        }
      }
  })    
  
  $('#other_razon_social').hide(); // by default hidden
  $('#other_giro').hide(); // by default hidden
  $('#order_other_boleta_o_factura option[value=""]').remove(); // remove default value.
  $('#shipping_address_taxid').hide();
  
  $('#order_other_boleta_o_factura').on('change', function() {
    var option = $("#order_other_boleta_o_factura option:selected").val();
    if(option == 'Factura Electrónica'){
      $('#other_razon_social').show();
      $('#other_giro').show();
      if($("#shipping_same_as_billing").is(":checked")){
        $('#order_shipping_address_taxid').attr("required","required");
        $('#shipping_address_taxid').show();
        $('#shipping_address_taxid').appendTo("#other");
      } else {
        $('#order_billing_address_taxid').attr("required","required");
        $('#billing_address_taxid').show();
        $('#billing_address_taxid').appendTo("#other");
      } 
    }else{
      $('#other_razon_social').hide();
      $('#other_giro').hide();
      $('#order_shipping_address_taxid').removeAttr('required');
      $('#shipping_address_taxid').hide();
      $('#order_billing_address_taxid').removeAttr('required');
      $('#billing_address_taxid').hide();
    }
  })
   
  });
</script>

The Chilean RUT validation can be further restricted by using this validation on checkout:

https://gist.github.com/tiagomatos/73b4166069d59e44906255edef498392