Silly parsing

1.md

This was actually used in a Website for detecting android version. The site has other delicacies I'm not sure what surprises me more. The fact it has been used like this or the fact that parseFloat is working.

detection-01.js

var userAgent = 'Mozilla/5.0 (Linux; Android 4.4; Nexus 5 Build/BuildID) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/30.0.0.0 Mobile Safari/537.36'
userAgent.slice(userAgent.indexOf("Android")+8)
// returns "4.4; Nexus 5 Build/BuildID) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/30.0.0.0 Mobile Safari/537.36"
parseFloat(userAgent.slice(userAgent.indexOf("Android")+8))
// returns 4.4 

detection-full.js

/* DO NOT DO THAT */
/* JS REDIRECT FOR MOBILE  */
 
// GLOBAL SCOPED FUNCTIONS
//New Script Shoptime
 
function setCookie(name, value) {
  document.cookie = name+"="+value+"; path=/";
}
 
function getCookie(name) {
  var nameEQ = name + "=";
  var ca = document.cookie.split(';');
  for(var i=0;i < ca.length;i++) {
    var c = ca[i];
    while (c.charAt(0)==' ') c = c.substring(1,c.length);
    if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
   }
   return null;
}
 
function deleteCookie(name) {
  document.cookie = name + '=; expires=Thu, 01 Jan 1970 00:00:01 GMT;';
}
 
function getQueryString() {
  var result = {}, queryString = location.search.substring(1),
          re = /([^&=]+)=([^&]*)/g, m;
 
  while (m = re.exec(queryString)) {
    result[decodeURIComponent(m[1])] = decodeURIComponent(m[2]);
  }
  return result;
}
 
(function(){
   var isAndroid23 = false;
   var userAgent = navigator.userAgent;
   var isMobile = /iP(hone|od)|Android.*Mobile/.test(userAgent);
   var mobileCookie = getCookie("NewMobileOptOut");
 
   if( userAgent.indexOf("Android") >= 0 ) {
     var androidversion = parseFloat(userAgent.slice(userAgent.indexOf("Android")+8));
     isAndroid23 = androidversion < 2.4;
     if (isAndroid23) { 
       // NEVER TRIGGER A REDIRECT FOR UNSUPPORTED ANDROID DEVICES
       return false;
     }
   }
   
   if (/(windows phone)|(iemobile)/i.test(userAgent)) {
     // NEVER REDIRECT ON UNSUPPORTED DEVICES
     return false;
   }
   
   // Get MobileOptOut from queryString
   var mobileQuery = getQueryString();
   if (mobileQuery) {
     mobileQuery = mobileQuery["MobileOptOut"];
   }
 
   // Update MobileOptOut cookie - 0 = delete, 1 = set
   if ( mobileQuery == '0' ) {
     deleteCookie("NewMobileOptOut");
   } else if ( mobileQuery == "1" ) {
     setCookie("NewMobileOptOut", mobileQuery);
   }
 
   // Redirect
   
   if (isMobile && (mobileCookie != "1" || mobileQuery == "0") && mobileQuery != "1" && mobileQuery != "2") {
     window.location = "http://m.shoptime.com.br" + window.location.pathname + window.location.search;
   }
   
   // OPT IN LINK
  
   if (isMobile) { 
     var sitemapLink = document.getElementsByClassName('sitemap-link');
     if (sitemapLink && sitemapLink.length > 0) { 
       sitemapLink[0].innerHTML = sitemapLink[0].innerHTML + "<p><a href=\"#\" onclick=\"setCookie('MobileOptOut', '0'); window.location = window.location.href.replace('MobileOptOut=1',''); return false;\">Acessar a Versao Mobile</a></p>";
     }
   }
 
 }());
 

Basically it fails for a UA such as Firefox for Android: Mozilla/5.0 (Android; Mobile; rv:30.0) Gecko/30.0 Firefox/30.0