Node.js - The function does not return data in select from table

I want to retrieve the unique id from the database and store them into the object (userslist).

Why can not I retrieve data into an object? Object userslist is empty {}

I have this function in Node.js:

getOnlineUsers: function()
    {
        var userslist = {};

        client.query(
            'SELECT DISTINCT Aid FROM online',
            function selectCb(err, results, fields) {
                if (err) {
                    throw err;
                }

                if (results.length > 0) {

                    for (var i = 0; i < results.length; i++) {
                        var reader = results[i];                        
                        userslist[reader['Aid']] = {
                            fbid: reader['Aid']
                        }
                    }       
                }
            }
            );
        return userslist; 
    }

Here's one example of what was discussed in the comments above.

Pass a callback to getOnlineUsers...

my_obj.getOnlineUsers(function(u_list) {

    /* do something with the user list */

});

And have getOnlineUsers receive the callback argument, and invoke it...

// receive the callback----v
getOnlineUsers: function(cb_func) {

    client.query(
        'SELECT DISTINCT Aid FROM online',
         function selectCb(err, results, fields) {
            if (err) {
                throw err;
            }

            var userslist = {}

            if (results.length > 0) {

                for (var i = 0; i < results.length; i++) {
                    var reader = results[i];                        
                    userslist[reader['Aid']] = {
                        fbid: reader['Aid']
                    }
                }       
            }
            cb_func(userslist); // <-- invoke the callback, passing the data
        });
}

This is one approach, but basically illustrates that the continuation of the flow of code needs to take place in the callback passed to client.query.