js judges whether the mobile phone system is android or ios

Without saying much, please look at the code:

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