JavaScript 浏览器版本判定

function BrowserType() 
 { 
   var userAgent = navigator.userAgent; //取得浏览器的userAgent字符串 
   var isOpera = userAgent.indexOf("Opera") > -1; //判断是否Opera浏览器 
   // var isIE = userAgent.indexOf("compatible") > -1 && userAgent.indexOf("MSIE") > -1 && !isOpera; //判断是否IE浏览器 
   var isIE=window.ActiveXObject || "ActiveXObject" in window
   // var isEdge = userAgent.indexOf("Windows NT 6.1; Trident/7.0;") > -1 && !isIE; //判断是否IE的Edge浏览器 
   var isEdge = userAgent.indexOf("Edge") > -1; //判断是否IE的Edge浏览器
   var isFF = userAgent.indexOf("Firefox") > -1; //判断是否Firefox浏览器 
   var isSafari = userAgent.indexOf("Safari") > -1 && userAgent.indexOf("Chrome") == -1; //判断是否Safari浏览器 
   var isChrome = userAgent.indexOf("Chrome") > -1 && userAgent.indexOf("Safari") > -1&&!isEdge; //判断Chrome浏览器 
  
   if (isIE)  
   { 
      var reIE = new RegExp("MSIE (\d+\.\d+);"); 
      reIE.test(userAgent); 
      var fIEVersion = parseFloat(RegExp["$1"]); 
      if(userAgent.indexOf('MSIE 6.0')!=-1){
        return "IE6";
      }else if(fIEVersion == 7) 
        { return "IE7";} 
      else if(fIEVersion == 8) 
        { return "IE8";} 
      else if(fIEVersion == 9) 
        { return "IE9";} 
      else if(fIEVersion == 10) 
        { return "IE10";} 
      else if(userAgent.toLowerCase().match(/rv:([d.]+)) like gecko/)){ 
            return "IE11";
        } 
      else
        { return "0"}//IE版本过低
    }//isIE end 
      
    if (isFF) { return "FF";} 
    if (isOpera) { return "Opera";} 
    if (isSafari) { return "Safari";} 
    if (isChrome) { return "Chrome";} 
    if (isEdge) { return "Edge";} 
  }//myBrowser() end 
 
  alert(BrowserType());