@modular-forms/react/dist/source/validation/custom.js

The modular and type-safe form library for React

/**
 * Creates a custom validation function.
 *
 * @param requirement The validation function.
 * @param error The error message.
 *
 * @returns A validation function.
 */
export function custom(requirement, error) {
    return async (value) => (Array.isArray(value) ? value.length : value || value === 0) &&
        !(await requirement(value))
        ? error
        : '';
}