emailValidator.ts

import { Validator } from 'formstate';
export const email: Validator<string | null | undefined> = (value: string | null | undefined) => {
  if (value == null || value == '') return null;
  value = value.trim();
  // src : http://emailregex.com/
  if (!/^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/g.exec(value)) {
    return "Not a valid email address";
  }
  return null;
}