1，jquery

获取scrollHeight：

$("div")[0].scrollHeight

$('div').prop('scrollHeight');

设置scrollTop

$(".chat-con").scrollTop(h);//这里没有引号，注意

 

2，js

var div = document.getElementById('scrolldIV');

div.innerHTML = div.innerHTML + 'time_' + now.getTime() + '<br />';

div.scrollTop = div.scrollHeight;

 

3，判断元素是否在页面中显示，浏览历史的时候，不到底部

function isNewInWindow(){

            // var div = document.getElementsByTagName("div");

            // div_length = div.length-6;

            // var l=$(".chat-con").children("div:last");

            var l=document.getElementsByClassName("chat-item");         

            if(isInWindow(l[l.length-1])){

                return true;

            }

            return false;

    }

    

    /*判定元素是否在界面内*/

    function isInWindow(x){     

         var h=$(".chat-con")[0].clientHeight;

            if(x.getBoundingClientRect().top >2*h ){

                // 元素低于当前界面

                return false;

            }

            else if(x.getBoundingClientRect().bottom < 0){

                // 元素高于当前界面

                return false;

            }

            return true;

    }