<div class="header"></div>
<div style="height: 1500px"></div>
<a href=".header" class="footer__link">To header</a>

$(".footer__link").click(function(){
  let elementClick = $(this).attr("href");
  let destination = $(elementClick).offset().top;
  $("html:not(:animated),body:not(:animated)").animate({scrollTop: destination}, 900);
  return false;
})