判斷ios和安卓系統

 var u = navigator.userAgent, app = navigator.appVersion;
      var isAndroid = u.indexOf('Android') > -1 || u.indexOf('Linux') > -1; //g
      var isIOS = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/); //ios終端
      if (isAndroid) {
      //安卓系統
      }
      if (isIOS) {
      //ios系統
      }
 

判斷pc和手機端

if(/Android|webOS|iPhone|iPod|BlackBerry/i.test(navigator.userAgent)) {
    window.location.href = "wap";
} else {
    window.location.href = "pc";
}