WordPress博客添加“返回顶部”按钮

<div id="full" style="width:88px; height:88px; position:fixed; right:0px; 
    bottom:0px; margin-left:0px; margin-bottom:0px; z-index:100; text-align:center; cursor:pointer;">
  <a>
    <img src="https://cdn.codefine.site:5443/wp-content/themes/thematic/gallery/totop2.png"
    border=0 width="55px" width="55px" alt="返回顶部">
  </a>
</div>
<script type="text/javascript">
  var isie6 = window.XMLHttpRequest ? false: true;
  function newtoponload() {
    var c = document.getElementById("full");
    function b() {
      var a = document.documentElement.scrollTop || window.pageYOffset || document.body.scrollTop;
      if (a > 0) {
        if (isie6) {
          c.style.display = "none";
          clearTimeout(window.show);
          window.show = setTimeout(function() {
            var d = document.documentElement.scrollTop || window.pageYOffset || document.body.scrollTop;
            if (d > 0) {
              c.style.display = "block";
              c.style.top = (400 + d) + "px"
            }
          },
          300)
        } else {
          c.style.display = "block"
        }
      } else {
        c.style.display = "none"
      }
    }
    if (isie6) {
      c.style.position = "absolute"
    }
    window.onscroll = b;
    b()
  }
  if (window.attachEvent) {
    window.attachEvent("onload", newtoponload)
  } else {
    window.addEventListener("load", newtoponload, false)
  }
  document.getElementById("full").onclick = function() {
    window.scrollTo(0, 0)
  };
</script>