Or condition not working in nodejs bot

Question

I am trying to add an or condition in my below piece of

var bot = new builder.UniversalBot(connector, [
    function (session) {
        if (!session.privateConversationData.greetingsDone) {
            session.send("Welcome to Ask Bot.");
            session.privateConversationData.greetingsDone = true;
            //Calling the intermediate dialog
            session.beginDialog('DelveDialog');
        }
        else{
            //If not the first call, go directly to QnADialog
            session.beginDialog('azureQnAMakerDialog') || session.beginDialog('downloadQnAMakerDialog')

        }
    }

also tried

session.beginDialog('azureQnAMakerDialog'||'downloadQnAMakerDialog')

But it is not working. I am not sure is it the problem of session.begindialog function or the problem of or condition.

Thanks in advance.