Asynchronous DB trnsactions?

Hi guys,
I have been created a local DB with one table and one row.
All is well until I try to select from it.
I use the following code:

function CheckForRow() {
    //Select the last (and hopefully only) row
    var query = "SELECT * FROM " + window.myTable + ";";
    window.db.transaction(function(tx) {
        tx.executeSql(query, [], DataHandler, Error);
    });
        //I want to test my result data here, but the data handler hasn't been invoked yet! 
}

function DataHandler(tx, resultSet){
    for (var i = 0; i < resultSet.rows.length; i++) {
            var row = resultSet.rows.item(i);
            window.myName = row['name'];
            window.myData = row['data'];
    }
}

What I am finding is that the handle function for the result data isn’t invoked until after the procedure that calls CheckForRow completes.
Does this mean that you can only effectively run asynch calls, or am I barking up the wrong tree? That would make for me a whole load of trouble!

regards
Ross