[support] calling url from javascript

how I can write my code for the URL written in JavaScript are from the root of the site and are independent of whether they are clean URL enabled or not? If y write this $.get('?q=mycallback', function(data){ }) The code sends this http://mysite.domain.com/current_url?q=mycallback I have enabled the Clean URL, if I disable this option, then If y write this $.get('/mycallback', function(data){ }) The code sends this http://mysite.domain.com/mycallaback some suggest?