I have a site with a option select drop down menu that all items are formerly written in English, now I just translated it into spanish but the dropdown items all flips back into English.

I use firebug to backtrack the loaded javascript files and watch the page during loading, I find that if I disable the javascript function on browser, I can view it then though but if i turn it on, the Spanish items are replaced.

Could you share a technique to debug this sort of javascript issue ?