How to determine client type using JS

<script type="text/javascript">
 var u = navigator.userAgent;
 var isAndroid = u.indexOf(&#39;Android&#39;) > -1 || u.indexOf(&#39;Adr&#39;) > -1; //android终端
 var isiOS = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/); //ios终端
 alert(&#39;是否是Android：&#39;+isAndroid);
 alert(&#39;是否是iOS：&#39;+isiOS);
</script>

<script type="text/javascript">
//判断访问终端
var browser={
 versions:function(){
  var u = navigator.userAgent, 
   app = navigator.appVersion;
  return {
   trident: u.indexOf(&#39;Trident&#39;) > -1, //IE内核
   presto: u.indexOf(&#39;Presto&#39;) > -1, //opera内核
   webKit: u.indexOf(&#39;AppleWebKit&#39;) > -1, //苹果、谷歌内核
   gecko: u.indexOf(&#39;Gecko&#39;) > -1 && u.indexOf(&#39;KHTML&#39;) == -1,//火狐内核
   mobile: !!u.match(/AppleWebKit.*Mobile.*/), //是否为移动终端
   ios: !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/), //ios终端
   android: u.indexOf(&#39;Android&#39;) > -1 || u.indexOf(&#39;Adr&#39;) > -1, //android终端
   iPhone: u.indexOf(&#39;iPhone&#39;) > -1 , //是否为iPhone或者QQHD浏览器
   iPad: u.indexOf(&#39;iPad&#39;) > -1, //是否iPad
   webApp: u.indexOf(&#39;Safari&#39;) == -1, //是否web应该程序，没有头部与底部
   weixin: u.indexOf(&#39;MicroMessenger&#39;) > -1, //是否微信 （2015-01-22新增）
   qq: u.match(/\sQQ/i) == " qq" //是否QQ
  };
 }(),
 language:(navigator.browserLanguage || navigator.language).toLowerCase()
}
</script>

/判断是否IE内核
if(browser.versions.trident){ alert("is IE"); }
//判断是否webKit内核
if(browser.versions.webKit){ alert("is webKit"); }
//判断是否移动端
if(browser.versions.mobile||browser.versions.android||browser.versions.ios){ alert("移动端"); }

currentLang = navigator.language; //判断除IE外其他浏览器使用语言
if(!currentLang){//判断IE浏览器使用语言
currentLang = navigator.browserLanguage;
}
alert(currentLang);

if (/(iPhone|iPad|iPod|iOS)/i.test(navigator.userAgent)) { //判断iPhone|iPad|iPod|iOS
 //alert(navigator.userAgent); 
 window.location.href ="iPhone.html";
} else if (/(Android)/i.test(navigator.userAgent)) { //判断Android
 //alert(navigator.userAgent); 
 window.location.href ="Android.html";
} else { //pc
 window.location.href ="pc.html";
};

<script>
　　//判断是否手机端访问
 var userAgentInfo = navigator.userAgent.toLowerCase();
 var Agents = ["android", "iphone",
    "symbianos", "windows phone",
    "ipad", "ipod"];
 var ly=document.referrer; //返回导航到当前网页的超链接所在网页的URL
 for (var v = 0; v < Agents.length; v++) {
  if (userAgentInfo.indexOf(Agents[v]) >= 0&&(ly==""||ly==null)) {
   this.location.href=&#39;http://m.***.com&#39;; //wap端地址
  }
 }
</script>

<script type="text/javascript">
 // borwserRedirect
 (function browserRedirect(){
  var sUserAgent = navigator.userAgent.toLowerCase();
  var bIsIpad = sUserAgent.match(/ipad/i) == &#39;ipad&#39;;
  var bIsIphone = sUserAgent.match(/iphone os/i) == &#39;iphone os&#39;;
  var bIsMidp = sUserAgent.match(/midp/i) == &#39;midp&#39;;
  var bIsUc7 = sUserAgent.match(/rv:1.2.3.4/i) == &#39;rv:1.2.3.4&#39;;
  var bIsUc = sUserAgent.match(/ucweb/i) == &#39;web&#39;;
  var bIsCE = sUserAgent.match(/windows ce/i) == &#39;windows ce&#39;;
  var bIsWM = sUserAgent.match(/windows mobile/i) == &#39;windows mobile&#39;;
  var bIsAndroid = sUserAgent.match(/android/i) == &#39;android&#39;;
  var pathname = location.pathname
  if(bIsIpad || bIsIphone || bIsMidp || bIsUc7 || bIsUc || bIsCE || bIsWM || bIsAndroid ){
  window.location.href = &#39;http://m.geekjc.com&#39;+pathname; //wap端地址
  }
 })();
 </script>