jQuery.ajaxSetup({ 
  'beforeSend': function(xhr) {xhr.setRequestHeader("Accept", "text/javascript")}
})

jQuery(document).ready(function() {
  jQuery("#orderform").submit(function() {
	jQuery.ajax({
		beforeSend:function(request){jQuery('#searching').show();jQuery('#add_button').attr('disabled', 'true');},
		complete:function(request){jQuery('#searching').hide();},
		data:jQuery.param(jQuery(this).serializeArray()),
		dataType:'script',
		type:'post',
		url:'check_avail'});
	return false;
  })
})