sorter is comparer function

from bloodhound documentation (https://github.com/twitter/typeahead.js/blob/master/doc/bloodhound.md#api): 
 sorter – A compare function used to sort matched datums for a given query.
link on "compare function" (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort) shows that it result value in set of [-1, 0, 1]
Merge pull request #3279 from aavezel/patch-1

sorter is comparer function