Function validateExactlyOne

3p/3p.js:241–248

* Throws an exception if data does not contains exactly one field * mentioned in the alternativeFields array. * @param {!Object} data * @param {!Array } alternativeFields

(data, alternativeFields)

 * @param {!Array<string>} alternativeFields
 */
function validateExactlyOne(data, alternativeFields) {
  userAssert(
    alternativeFields.filter((field) => data[field]).length === 1,
    '%s must contain exactly one of attributes: %s.',
    data.type,
    alternativeFields.join(', ')
  );
}

/**
 * Throws a non-interrupting exception if data contains a field not supported