Medium-FormValidation-useForm.js

export function useForm (defaultValues, invalidAttr = { error: true }) {
  const [values, setValues] = useState(defaultValues);
  const [mounted, setMounted] = useState(false);
  const [formErrors, setFormErrors] = useState([]);

  const handleError = useCallback((name, isValid) => {
    let errors = formErrors;
    const index = errors.findIndex(error => error === name);

    if (!isValid) {
      if (index < 0) errors.push(name);
    } else {
      if (index > -1) errors.splice(index, 1);
    }

    setFormErrors(errors);
  }, [formErrors]);

  useEffect(() => {
    setMounted(true);
  }, []);

  const useInput = (name, validation) => useFormInput({
    name,
    validation,
    values,
    setValues,
    defaultInvalidAttr: invalidAttr,
    handleError
  });

  return {
    values,
    setValues,
    useInput,
    errors: formErrors,
    isValid: mounted && !formErrors.length
  };
}