For simpler, one-off calculations where you just want to leverage the power of the Qlik Sense engine, qStringExpression and qValueExpression are the little sisters of qHyperCube and qListObject. They work using the same concept as the rest but on a simpler level: all you need to do is define a Qlik expression, and the engine will return to you its result in a promise:

var app = qlik.currApp(this);
app.createGenericObject({
    user: {
        qStringExpression:"=OSUser()"
    }, 
    version: {
        qStringExpression:"=EngineVersion()"
    }, 
    fields: { 
        qValueExpression:"=Count (DISTINCT $Field)"
    } 
}, function ( reply ) { 
    var str = "Version:" + reply.version + 
        str+= " Number of Fields:"+reply.fields; 
    if(reply.user) { 
        str += " User:" + reply.user; 
    }
    console.log(str)
}

Using those object definitions is very handy in conjunction with other objects, such as a qHyperCube.