I have an iframe and I want to set the scroll position to that

<iframe id="quraniframe" width="100%" height="1100px" src="https://quran.com/1?locale=fa" frameborder="0"></iframe>

and this is my JavaScript code's

    $(function() {

        $('#quraniframe').contents().scrollTo(0, 30);
        window.alert("scroll = " + scroll);
})

and this is result in an alert

scroll = undefined

Actually, I use this code to and no effect in iframe content