offsetHeight:Retrieves the height of the object relative to the layout or coordinate parent, as specified by the offsetParent property.
scrollTop :Sets or retrieves the distance between the top of the object and the topmost portion of the content currently visible in the window.
scrollTop :Sets or retrieves the distance between the top of the object and the topmost portion of the content currently visible in the window.
++ml:就是ml加1
scrollTop:获取或设置此元素边缘与其内容的上边缘之间的距离,也就是行距
lis[0].parentNode.appendChild(lis[0]);:增加节点
++ml:就是ml加1
scrollTop:获取或设置此元素边缘与其内容的上边缘之间的距离,也就是行距
lis[0].parentNode.appendChild(lis[0]);:增加节点