jQuery-UI autocomplete with multiple comma-separated values from a JSON remote source

example.js

    $(function() {
        function split( val ) {
          return val.split( /,\s*/ );
        }

        function extractLast( term ) {
          return split( term ).pop();
        }

        $( "#new_interest" ).autocomplete({
          source: function( request, response ) {
                    $.getJSON( "/tags.json", {
                      term: extractLast( request.term )
                    }, response );
                  },
          select: function( event, ui ) {
                    // Add the selected term appending to the current values with a comma
                    var terms = split( this.value );
                    // remove the current input
                    terms.pop();
                    // add the selected item
                    terms.push( ui.item.value );
                    // join all terms with a comma
                    this.value = terms.join( ", " );
                    return false;
                  },
          focus: function() {
                   // prevent value inserted on focus when navigating the drop down list
                   return false;
                 }
        });
      });

tags.json

[{
    "id": 28,
    "name": "sex",
    "value": "sex"
}, {
    "id": 29,
    "name": "drugs",
    "value": "drugs"
}, {
    "id": 30,
    "name": "rock and roll",
    "value": "rock and roll"
}]