Bug in the Wikipedia main web page - Wikitech-l

28 Jan 2014


      Dear all,
We are researchers at KAIST in Korea working on finding JavaScript bugs in web pages.  While analyzing top websites from Alexa.com, we found an issue, which seems to be a bug, on the Wikipedia main web page (wikipedia.org).  We would be grateful if you can either confirm that it is a bug and even better fix it or let us know what we're missing.
Here's the issue.  When a user selects a language in which search results are displayed via the language selection button from the Wikipedia main web page, the following JavaScript function is executed:
1     function setLang(lang) {
 2         var uiLang = navigator.language || navigator.userLanguage, date = new Date();
 3 
 4         if (uiLang.match(/^\w+/) === lang) {
 5             date.setTime(date.getTime() - 1);
 6         } else {
 7            date.setFullYear(date.getFullYear() + 1);
 8         }
 9 
10       document.cookie = "searchLang=" + lang +  ";expires=" + date.toUTCString() +  ";domain=" + location.host + ";";
11   }
Depending on the evaluation result of the conditional expression on line 4, "uiLang.match(/^\w+/) === lang", the function leaves or dose not leave the selected language information on  the user's computer through a cookie.  But we found that the expression, "uiLang.match(/^\w+/) === lang", always evaluates to false, which results in that the function always leaves cookies on users' computers.  We think that changing the contidional expression, "uiLang.match(/^\w+/) === lang", to the expression, "uiLang.match(/^\w+/) == lang", will solve the problem.
This problem may occur in the main web pages of all the Wikimedia sites.  Could you kindly let us know what you think?  Thank you in advance.
Best,
Changhee Park and Sukyoung Ryu