I am using Twitter\'s typeahead.js (https://github.com/twitter/typeahead.js/) on an input field which is pre filled from a query string. After loading the page, i\'d like to
Looking through the source code, it appears to store a TypeaheadView object in the element data under the key typeahead. This TypeaheadView object has an internal method, _showDropdown, which is internally bound to the focus event (and a few others).
I would not recommend doing this, but you should be able to call that internal method manually:
$('#yourTypeaheadElement').data('typeahead')._showDropdown();
Alternatively, have you just tried simply focusing your typeahead element when the page loads (after initializing it as a typeahead element, of course):
// after page loads and yourTypeaheadElement is initialized as a typeahead
$('#yourTypeaheadElement').focus();