I am trying to use twitter bootstrap to get the manufacturers from my DB. Because twitter bootstrap typeahead does not support ajax calls I am using this fork: https://gist.github.com/1866577 In that page there is this comment that mentions how to do exactly what I want to do. The problem is when I run my code I keep on getting: Uncaught TypeError: Cannot call method 'toLowerCase' of undefined I googled around and came tried changing my jquery file to both using the minified and non minified as well as the one hosted on google code and I kept getting the same error. My code currently is as follows: $('#manufacturer').typeahead({ source: function(typeahead, query){ $.ajax({ url: window.location.origin+"/bows/get_manufacturers.json", type: "POST", data: "", dataType: "JSON", async: false, success: function(results){ var manufacturers = new Array; $.map(results.data.manufacturers, function(data, item){ var group; group = { manufacturer_id: data.Manufacturer.id, manufacturer: data.Manufacturer.manufacturer }; manufacturers.push(group); }); typeahead.process(manufacturers); } }); }, property: 'name', items:11, onselect: function (obj) { } }); on the url field I added the window.location.origin to avoid any problems as already discussed on another question Also before I was using $.each() and then decided to use $.map() as recomended Tomislav Markovski in a similar question Anyone has any idea why I keep getting this problem?! Thank you