js如何判断手机型号

function getOS() {
  //获取用户代理
  var ua = navigator.userAgent;
  if (ua.indexOf("Windows NT 5.1") != -1) return "Windows XP";
  if (ua.indexOf("Windows NT 6.0") != -1) return "Windows Vista";
  if (ua.indexOf("Windows NT 6.1") != -1) return "Windows 7";
  if (ua.indexOf("iPhone") != -1) return "iPhone";
  if (ua.indexOf("iPad") != -1) return "iPad";
  if (ua.indexOf("Linux") != -1) {
    var index = ua.indexOf("Android");
    if (index != -1) {
      //os以及版本
      var os = ua.slice(index, index+13);

      //手机型号
      var index1 = ua.lastIndexOf(";");
      var index2 = ua.indexOf("Build");
      var type = ua.slice(index1+1, index2);
      return type + os;
    }else {
      return "Linux";
    }
  }
  return "未知操作系统";
}
console.log('Your OS: '+ getOS());