returning results to outer function

Not quite sure how to return result to outer function, i want to call getListOfUsers() and get returned list of results

function getListOfUsers() {
    userlist.getUsers(function(next, res) {
       var result = JSON.parse(res);
       var listOfUsers = result.members.map(function (mem) {
            return mem.name;
        });
    });
}

If i return outside of the map, it will obviously return undefined, or null if i define it outside and initiate it inside. Using promises leaves me in same situation where my return is inside the 'then' function. Whats common practice here?