validation plugin - two languages

validation plugin - two languages

I am sorry, but i cannot find any solution, how to have a multiple language error messages. When I use localisation javascript file messages_cs.js, the english is not working anymore, when I validate form from browser which has english in default settings and .  The documentation of jquery validator plugin tells nothing about this problem. . When I ask google search for°"jquery validation multiple language error messages" - there is a lot of results, but nothing works... 

My website is in english and czech language. I am using navigator.language javascript function to setup all inputs "lang" attributes to "cs" or "en", but it is not working.

Validator is still using messages_cs.js, not english. 

I have found solution with this javascript code <script type="text/javascript" src="js/localization/messages_<%= Locale.getDefault().getLanguage() %>.js" /></script>, but i think this is nonsense...

Can you help me, please?