regExp validator not working

Summary

While using the validator It keeps saying Value '****' must match this pattern: ''. (where **** is my input value)

Content

Hi guys, I keep receiving this error while trying to use the regExp validator on the input text field. I tried different option in the validators.options field and It keeps telling me this: Value '****' must match this pattern: ''.

what I need is to only input letters OR numbers depending on what option I want.

What i tried literally: options: {pattern: '[a-zA-Z]{3,}'}, {"pattern": '[0-9]{3,}'}, {"pattern": '[a-zA-Z]{3,}'}

Can anyone help me on what to write on the validators.options field? Thank you!!