Plural function for russian language

js_plural_ru.js

function plural_str(i, str1, str2, str3){
  function plural (a){
    if ( a % 10 == 1 && a % 100 != 11 ) return 0
    else if ( a % 10 >= 2 && a % 10 <= 4 && ( a % 100 < 10 || a % 100 >= 20)) return 1
    else return 2;
  }

  switch (plural(i)) {
    case 0: return str1;
    case 1: return str2;
    default: return str3;
  }
}