I need a regex that checks if there are more than two letters.

It should only allow one letter.

But allow numbers.

For example

* 1a is good
* 1ab is bad
* 11 is good
* 11ab is bad

I have one, it also takes as wrong when there are any numbers... I do want to allow numbers. Just not more than one letter.

This is my rgex:

```
export const onlyOneCharacter = (string) => {
  return /^[A-Za-z]{0,1}$/.test(string) ? undefined : "wrong";
};

```

Returning undefined mean its correct, so it doesnt show any validation error.