js 浏览器判断

function getBrowser() {

        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 isFF = userAgent.indexOf('Firefox') > -1 //判断是否Firefox浏览器

        var isSafari = userAgent.indexOf('Safari') > -1 //判断是否Safari浏览器

    var isChrome = navigator.userAgent.match(/chrome\/[\d.]+/gi) // 是否chrome

        if (isIE) {

          // var IE5 = IE55 = IE6 = IE7 = IE8 = false, IE9=false

          var reIE = new RegExp('MSIE (\\d+\\.\\d+);')

          reIE.test(userAgent)

          var fIEVersion = parseFloat(RegExp['$1']),

            IE55 = fIEVersion == 5.5,

            IE6 = fIEVersion == 6.0,

            IE7 = fIEVersion == 7.0,

            IE8 = fIEVersion == 8.0,

            IE9 = fIEVersion == 9.0

          if (IE55) {

            return 'IE55'

          }

          if (IE6) {

            return 'IE6'

          }

          if (IE7) {

            return 'IE7'

          }

          if (IE8) {

            return 'IE8'

          }

          if (IE9) {

            return 'IE9'

          }

        }//isIE end

        if (isFF) {

          return 'FF'

        }

        if (isOpera) {

          return 'Opera'

        }

        if(isSafari) {

           return 'Safari'

        }

        if(isChrome) {

           return 'Chrome'

        }

      }