項目在低版本瀏覽器下不兼容？友情提示客戶升級瀏覽器（如下只針對IE瀏覽器）

(function (window) {
  var win = window,
    sys = {},
    ua = navigator.userAgent.toLowerCase();
  (/msie\s+(\d+)/.test(ua)) ? sys.ie = RegExp.$1 :
    (/firefox\/(\d+)/.test(ua)) ? sys.firefox = RegExp.$1 :
      (/chrome\/(\d+)/.test(ua)) ? sys.chrome = RegExp.$1 :
        (/opera.(\d+)/.test(ua)) ? sys.opera = RegExp.$1 :
          (/version\/(\d+).*safari/.test(ua)) ? sys.safari = RegExp.$1 : 0;
  if (sys.ie && sys.ie < 11) {
    // 瀏覽器版本太低
    var divDOM = document.createElement("div");
    divDOM.id = "alert_browser";
    divDOM.innerHTML = "<p style='z-index:999999;font-family:Georgia,Serif;width:100%;height:50px;line-height:50px;font-size:14px;margin:0;padding:0;" +
      "text-align:center;position:absolute;left:0;top:0;" +
      "background-color:#FAFAD2;border-bottom: 1px solid #DCDCDC'>系統檢測您的瀏覽器版本太低，請升級您的瀏覽器&nbsp;&nbsp;" +
      // 瀏覽器下載圖標所有在這裏
      "<a target='_blank' href='http://chrome.360.cn/' style='margin:0 10px;'><img style='vertical-align:middle;border:none;' src='http://i6.download.fd.pchome.net/g1/M00/08/04/oYYBAFN0Lg2IVp_SAADF669ldkIAABh7QKbKLUAAMYD687.png' width='30' height='30' alt='360急速瀏覽器' /></a>" +
      "<a target='_blank' href='http://dl.pconline.com.cn/download/51614-1.html' style='margin:0 10px;'><img style='vertical-align:middle;border:none;' src='https://cdn1.iconfinder.com/data/icons/smallicons-logotypes/32/chrome-512.png' width='30' height='30' alt='谷歌瀏覽器' /></a>" +
      "<a target='_blank' href='https://support.microsoft.com/zh-cn/help/17621/internet-explorer-downloads' style='margin:0 10px;'><img style='vertical-align:middle;border:none;' src='https://vignette1.wikia.nocookie.net/kirby/images/4/40/IE.png/revision/latest?cb=20110716080705&path-prefix=en' width='30' height='30' alt='IE最新版本' /></a>" +
      "<p>";
    document.body.appendChild(divDOM)
  }
})(window)