[brexit2000]

;(function(){
   var str = 'аеёиоуыэюя'
   check = function(letter){
      if(str.indexOf(letter) > -1) return "vowel"
      return "consonant"
   }
}())


checkForm = function(){
   var warn = "введите пароль в русской раскладке"
   var pass = prompt(warn)
   if(/[^а-яё]/i.test(pass)) {
      alert(warn)
      return checkForm()
   }
   pass = pass.split("")
   return (pass.filter(function(letter) {return check(letter) === "vowel"}).length - 3) === pass.filter(function(letter) {return check(letter) === "consonant"}).length
}

alert(checkForm())