如何使回到顶部锚链接平滑滚动

Question

i'm trying to make the back to the top button on click to be smooth scrolling but i'm stuck.. at the moment this code works but its not smooth scrolling to the top of the page.. can anyone help me on this?

<a id="BackToTop" href="#" title="Back to the top" class="back-to-top hide">
  <span>⌃</span>
</a>
<style>
  .back-to-top {
    position: fixed;
    bottom: 20px;
    right: 25px;
    color: #999;
    background-color: #243066;
    z-index: 60000;  
  }
  .back-to-top span{
     height: 47px;
  }
  .hide {
    display: none!important;
  }
  .back-to-top:hover {
    box-shadow: 1px 1px 25px #9e9e9e;
  }
</style>
<script>
  (function() {
    function trackScroll() {
      var scrolled = window.pageYOffset;
      var coords = 300;

      if (scrolled > coords) {
        goTopBtn.classList.remove('hide');
      }
      if (scrolled < coords) {
        goTopBtn.classList.add('hide');
      }
    }

    function backToTop() {
      if (window.pageYOffset > 0) {
        window.scrollBy(0, -80);
        setTimeout(backToTop, 0);
      }
    }

    var goTopBtn = document.querySelector('.back-to-top');

    window.addEventListener('scroll', trackScroll);
    goTopBtn.addEventListener('click', backToTop);
  })();
</script>

Answer 1

Modern browsers (everything but IE) support a scrollTo method on the window object which you can pass smooth scrolling behaviour to:

window.scrollTo({ top: 0, left: 0, behavior: 'smooth'});

There are also variations on this such as element.scrollIntoView()

Answer 2

You may use that

document.getElementById('id').scrollIntoView({
  behavior: 'smooth'
});

Answer 3

document
      .getElementById("id")
      .scrollIntoView({ block: "start", behavior: "smooth" });

Answer 4

body{ scroll-behaviour: smooth; }