jQuery实现返回顶部按钮功能

• html结构

• <div class="toolbar">
              <a href="javascript:;" class="toolbar-item">
                  <span class="toolbar-btn" id="backtop">
                      <i class="toolbar-icon icon-upload2"></i>  //图标字体
                      <span class="toolbar-text">返回<br />顶部</span>
                  </span>
              </a>
  </div>

• css样式

• .toolbar{
      position: fixed;
      right: 10px;
      bottom: 20px;
  }
  .toolbar-item{
      position: relative;
      display: block;
      width: 50px;
      height: 50px;
  
  
      &:hover{
          .toolbar-icon{
              top: -@toolbar-size;
          }
          .toolbar-text {
              top: 0;
          }
      }
  }
  .toolbar-btn{
      position: absolute;
      left: 0;
      top: 0;
      width: 50px;
      height: 50px;
      overflow: hidden;
  
      .toolbar-icon{
          position: absolute;
          left: 0;
          top: 0;
          width: 50px;
          height: 50px;
          background-color: #ccc;
          font-size: 30px;
          color: #fff;
          text-align: center;
          transition: top 1s;
      } 
      .toolbar-text{
          position: absolute;
          left: 0;
          top: 50px;
          width: 50px;
          height:50px;
          background-color: #A0A0A0;
          font-size: 14px;
          color: #fff;
          text-align: center;
          transition: top 1s;
      }
  }

• jQuery实现返回顶部

• <script type="text/javascript">
          $(function() {
              $('#backtop').on('click',move);   //绑定点击事件，也可写成：$("#backtop").click(function(){  //代码   })
              $(window).on('scroll',function(){
                  checkposition( $(window).height() );
              });
  
              function move() {
                  $('html,body').animate({
                      scrollTop: 0
                  },800);
              }
  
              function checkposition(H) {
                  if($(window).scrollTop() > H){
                      $('#backtop').fadeIn();
                  }
                  else{
                      $('#backtop').fadeOut();
                  }
              }
          })
  </script>

   

至此，返回顶部按钮功能基本实现