js判断不同的系统，调用不同的代码，例如安卓和IOS

<script type="text/javascript">  

            function browserRedirect() {  

                var sUserAgent = navigator.userAgent.toLowerCase();  

                var bIsIpad = sUserAgent.match(/ipad/i) == "ipad";  

                var bIsIphoneOs = sUserAgent.match(/iphone os/i) == "iphone os";  

                var bIsMidp = sUserAgent.match(/midp/i) == "midp";  

                var bIsUc7 = sUserAgent.match(/rv:1.2.3.4/i) == "rv:1.2.3.4";  

                var bIsUc = sUserAgent.match(/ucweb/i) == "ucweb";  

                var bIsAndroid = sUserAgent.match(/android/i) == "android";  

                var bIsCE = sUserAgent.match(/windows ce/i) == "windows ce";  

                var bIsWM = sUserAgent.match(/windows mobile/i) == "windows mobile";  

                if (!(bIsIpad || bIsIphoneOs || bIsMidp || bIsUc7 || bIsUc || bIsAndroid || bIsCE || bIsWM) ){  

                    window.location.href=B页面;

                } 

            }  

            browserRedirect();

</script>