scrollLeft/scrollTop/scrollHeight

scrollHeight  :  It includes the element's padding, but not its border or margin.This property will round the value to an integer. If you need a fractional value, use Element.getBoundingClientRect().

scrollLeft:

http://runjs.cn/code/szgoses4

scrollBottom:

http://runjs.cn/code/g17tputa  判断页面是否到达底部：ele.scrollHeight - ele.scrollTop === ele.clientHeight;

http://blog.csdn.net/wp270280522/article/details/41894457

https://yq.aliyun.com/articles/20710

http://blog.csdn.net/woxueliuyun/article/details/8638427  clientHeight/offsetHeight