右侧栏滚动到顶部自动固定教程代码

直接上代码:

<script>
    window.onscroll = function () {
          var topScroll = document.documentElement.scrollTop;//滚动的距离,距离顶部的距离
          var bignav = document.getElementsByClassName("aside")[0];//获取到导航栏id
          var left = document.getElementsByClassName("aside")[0].getBoundingClientRect().left;      
          var width=document.getElementsByClassName("aside")[0].getBoundingClientRect().width; 
     if (topScroll > 210 && 
Math.abs(topScroll-document.documentElement.scrollHeight)>600) { //当滚动距离大于250px时执行下面的东西        
          bignav.style.position = 'fixed';        
          bignav.style.top = '10px';        
          bignav.style.left = '' + left + 'px';        
          bignav.style.width = '' + width + 'px';        
          bignav.style.zIndex = '9999';      
          } else {//当滚动距离小于250的时候执行下面的内容，也就是让导航栏恢复原状        
          bignav.style.position = 'static';      
          }    
       }  
</script>