Get browser language via JavaScript

This is simple cross-browser solution:

var lang = (navigator.language || navigator.systemLanguage || navigator.userLanguage || 'en').substr(0, 2).toLowerCase();


And usage example:

var lang = (navigator.language || navigator.systemLanguage || navigator.userLanguage || 'en').substr(0, 2).toLowerCase();
if (lang == 'ru') {
    document.write('Specific Russian text');
} else {
    document.write('Common English text');
}