滚动返回页面顶部的JS特效

 

实现动态滚动的步骤：

（1）加入JS代码：

<script language="javascript">

var goto_top_type = -1;

var goto_top_itv = 0;

function goto_top_timer() {

      var y = goto_top_type == 1 ? document.documentElement.scrollTop : document.body.scrollTop;

         var moveby = 15;

          

         y -= Math.ceil(y * moveby / 100);

         if (y < 0) {

         y = 0;

         }

          

         if (goto_top_type == 1) {

         document.documentElement.scrollTop = y;

         }

         else {

         document.body.scrollTop = y;

         }

          

         if (y == 0) {

         clearInterval(goto_top_itv);

         goto_top_itv = 0;

         }

}

 

function goto_top() {

         if (goto_top_itv == 0) {

                  if (document.documentElement && document.documentElement.scrollTop) {

                  goto_top_type = 1;

                  }

                  else if (document.body && document.body.scrollTop) {

                  goto_top_type = 2;

                  }

                  else {

                  goto_top_type = 0;

                  }

                   

                  if (goto_top_type > 0) {

                  goto_top_itv = setInterval('goto_top_timer()', 50);

                  }

         }

}

</script>

 

（2）加入链接：

<a href="javascript:void(0)" onclick="goto_top()">【返回顶部】</a>