How do I use nodejs Mysql to get my data into the function after callback

So I'm trying to use nodejs mysql to access my locally running database that I am using for development. Everything is running correctly and I am able to make successful queries to the server and get the data back.

I have the function I created below which I am module.exports so that it is accessible from within my server where it is invoked and the loadExp() method is called.

var dataStore = function (connection) {

    this.con = connection;
    this.clientArr = new Map();

    /**
     * Loads all of the user experiences into the array.
     */
    this.loadExp = function () {

        var output = 'err';

        loadData(this.con, function (err, result) {
            console.log(err || result);
            output = result.uuid;
        });

        console.log(output);
    };

    function loadData(con, callback) {
        con.query('SELECT * FROM exp', function (err, rows, fields) {
            if (err) throw err;
            callback(null, rows);
        });
    }

    /**
     * Returns the value of a client from within the hash map.
     * @param id
     * @returns {*|String}
     */
    this.getClient = function (id) {
        var value = this.clients.get(id);
        if (value != null) {
            return value;
        } else {
            return 'err';
        }
    };

    /**
     * Returns a full list of clients.
     * @returns {Map}
     */
    this.getClientList = function () {
        return this.clientArr;
    };

    /**
     * Creates a new instance of a client within the database and also within our datastore.
     * @param id
     * @param client
     */
    this.addClient = function (id, client) {
        this.clientArr.set(id, client);
    };

};

module.exports = dataStore;

Now I would like to make use of my this.addClient function outlined at the bottom of this function but I can never get my data in scope to make this possible and I'm stuck for how I would get this data in scope so that it is usable.

via li x