jquery bug in IE for selecting field set to display

gistfile1.js

$('#exhibitor_exhibitor_registration_level_id').bind('change', function(){
     var selected_index = $(this).get(0).selectedIndex;
     var type = $(this).get(0).options[selected_index].text.split(':')[0].toLowerCase().trim();
     var type_name = type.match(/school/) ? "school" : "business";
     $(".entity_name").hide();
     $("." + type_name).show();
});

and the fix is (mostly because IE does not implement trim() for some inexplicable reason):
$('#exhibitor_exhibitor_registration_level_id').bind('change', function(){
var selected_index = $(this)[0].selectedIndex;
var type = $($(this)[0].options[selected_index]).text();
type = $.trim(type.split(':')[0].toLowerCase());
var type_name = /school/.test(type) ? "school" : "business";
$(".entity_name").hide();
$("." + type_name).show();
});