I do it all the time. As long as you are connecting to the same server that you loaded the page from, then you are all set. This is how I normally make JSON requests:
var url = '{{=URL('some.json')}}/';
jQuery.getJSON(url).success(function(data) {
// finished successfully
alert(data);
}).fail(function(err) {
// ajax failed
alert(err);
});
There are many ways to do this, but this one seems to be the most robust
for me, as it can catch connection and server errors.

