js判断浏览器的类型，动态调整div布局

最近写页面用bootstrap和amazeUi然后发现自己写的部分和两个框架做重合时，页面大小变化后有的元素变得很乱，很乱无奈只好用js判断 window.onscroll = function scrollfunction() {}根据下滑的高度来动态设置一些元素的布局，发现还是有点问题宽度有。干脆隐藏掉一些。

 window.onscroll = function scrollfunction() {
            var dis = document.documentElement.scrollTop || document.body.scrollTop;
            var count = ;
            if (dis > ) {
                var userAgent = navigator.userAgent;
                if(userAgent.indexOf("Firefox")>-){

                $('#forumDiv').css({"position": "absolute", "left": "380px  "})
                $('#userInfoDiv').css({"position": "fixed", "width": "300px", "top": "50px"})
                $('#hotKeyDiv').css({"position": "fixed", "right": "100px", "width": "300px", "top": "50px","display":"none"})
                $('#toTop').css({"bottom":"150px"})
                }else{

                $('#forumDiv').css({"position": "absolute", "left": "380px  "})
                $('#userInfoDiv').css({"position": "fixed", "width": "400px", "top": "50px"})
                $('#hotKeyDiv').css({"position": "fixed", "right": "100px", "width": "400px", "top": "50px"})
                $('#toTop').css({"bottom":"150px"})
                }
                count = ;

            }

            else {
                $('#toTop').css({"bottom":"300px"})
                // document.getElementById("institutionDiv").style.display="block";
                // document.getElementById("upDiv").style.display="block";
                $('#forumDiv').css({"position": "", "left": "  "})
                $('#userInfoDiv').css({"position": "", "width": ""})
                $('#hotKeyDiv').css({"position": "", "right": "", "width": "","display":"block"})
            }
        }
        $(window).resize(function () {
          var windowHeight= $(window).width();
          if(windowHeight<){
              document.getElementById('hotKeyDiv').style.display="none"
          }else{
              document.getElementById('hotKeyDiv').style.display="block"
          }
        })

加上个判断浏览器的类型。。

    var userAgent = navigator.userAgent; //取得浏览器的userAgent字符串
    var isOpera = userAgent.indexOf("Opera") > -;
    //判断是否Opera浏览器
    if (isOpera) {
        return "Opera"
    };
    //判断是否Firefox浏览器
    if (userAgent.indexOf("Firefox") > -) {
        return "FF";
    }
    //判断是否chorme浏览器
    if (userAgent.indexOf("Chrome") > -){
        return "Chrome";
    }
    //判断是否Safari浏览器
    if (userAgent.indexOf("Safari") > -) {
        return "Safari";
    }
    //判断是否IE浏览器
    if (userAgent.indexOf("compatible") > - && userAgent.indexOf("MSIE") > - && !isOpera) {
        return "IE";
    }
    //判断是否Edge浏览器
    if (userAgent.indexOf("Trident") > -) {
        return "Edge";
    };