Check if IndexedDB database exists

Is there a way to check if an IndexedDB database already exists? When a program tries to open a database that does not exists the database is created. The only way that I can think of is something like the following, where I test if an objectStore already exists, if it doesn't, the database is deleted:

var dbexists=false;
var request = window.indexedDB.open("TestDatabase");
request.onupgradeneeded = function(e) {
    db = e.target.result;
    if (!db.objectStoreNames.contains('todo')) {
       db.close();
       indexedDB.deleteDatabase("TestDatabase");
    } else {
       dbexists=true;
    }
}