function zipchanged() {
  var zip = $.trim(this.value);
  var form_id = $(this).parents('form').attr('id');
  $.get('/index.php?ACT=check_zip_code&zip='+zip, function(resp){
    if(resp == '-1') {
      $('#'+form_id+' .a2c_img').attr("src", "/images/icons/error.png");
      $('#'+form_id+' .a2c_alert').html('');
      $('#'+form_id+' .a2c_paypal_button').attr('disabled', true).addClass('disabled').fadeTo(50, 0.5);
    } else {
      $('#'+form_id+' .a2c_img').attr("src", "/images/icons/success.png");
      $('#'+form_id+' .a2c_alert').html(resp);
      $('#'+form_id+' .a2c_paypal_button').attr('disabled', false).removeClass('disabled').fadeTo(50, 1);
    }
  });
}
$(function(){
  $('.a2c_paypal_button').fadeTo(50, 0.5);
  $('.a2c_zip').keyup(zipchanged).change(zipchanged);
});