How do I get return value from HTML Element function?

When I add new elements into hmtl elements, it sometimes forces to scroll to the top. Then I created a function inside HTML Element as follows:

function GetScrollY()

{

return window.pageYOffset || document.documentElement.scrollTop;

}

But I don't know how to call it in C3 to get the return value of scroll Y position, to use it to set the HTML scroll position after 'Add new element' action.

I use script:

alert(runtime.callFunction(GetScrollY()))

But it doesn't work

Is there any way to solve this?

Thanks