if(elem.jump_ref)
{
    if(document.body.scrollTop || document.body.scrollTop === 0)
    {
        document.body.scrollTop = elem.jump_ref.offsetTop - page_top_padding;
    }
    else if(window.pageYOffset || window.pageYOffset === 0)
    {
        window.pageYOffset = elem.jump_ref.offsetTop - page_top_padding;
    }
}