How can I detect a Scrollbar presence ( using Javascript ) in HTML iFrame?

How can I detect a Scrollbar presence ( using Javascript ) in HTML iFrame ?

I have already tried :

        var vHeight = 0;
        if (document.all) {
          if (document.documentElement) {
            vHeight = document.documentElement.clientHeight;
          } else {
            vHeight = document.body.clientHeight
          }
    } else {
      vHeight = window.innerHeight;
    }

    if (document.body.offsetHeight > vHeight) {
      //when theres a scrollbar
    }else{
      //when theres not a scrollbar
    }

And I also had tried :

           this.scrollLeft=1;
    if (this.scrollLeft>0) {
        //when theres a scrollbar
        this.scrollLeft=0;
        }else{
        //when theres not a scrollbar
        return false;
    }

With no success..

I have searched the javascript objets on DOM Inspector, but didn't find anything.

Is is possible to detect a scrollbar presence in a iframe in javacscript ?

The iframe content comes from the same domain.

No success until now..

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