String.prototype.isUpperCase = function() {
  if (!/^[a-zA-Z]+$/.test(this.toString())) return false;
  return this.toString() === this.toUpperCase()
}
String.prototype.isLowerCase = function() {
  if (!/^[a-zA-Z]+$/.test(this.toString())) return false;
  return this.toString() === this.toLowerCase()
}

helpful. thought id send it