Function lookup

lib/internal/dns/promises.js:196–239

* Get the IP address for a given hostname. * @param {string} hostname - The hostname to resolve (ex. 'nodejs.org'). * @param {object} [options] - Optional settings. * @param {boolean} [options.all] - Whether to return all or just the first resolved address. * @param {0 | 4 | 6} [options.family]

(hostname, options)

 * @returns {Promise<object>}
 */
function lookup(hostname, options) {
  let hints = 0;
  let family = 0;
  let all = false;
  let dnsOrder = getDefaultResultOrder();

  // Parse arguments
  if (hostname) {
    validateStringWithoutNullBytes(hostname, 'hostname');
  }

  if (typeof options === 'number') {
    validateOneOf(options, 'family', validFamilies);
    // Coerce -0 to +0.
    family = options + 0;
  } else if (options !== undefined && typeof options !== 'object') {
    throw new ERR_INVALID_ARG_TYPE('options', ['integer', 'object'], options);
  } else {
    if (options?.hints != null) {
      validateNumber(options.hints, 'options.hints');
      hints = options.hints >>> 0;
      validateHints(hints);
    }
    if (options?.family != null) {
      validateOneOf(options.family, 'options.family', validFamilies);
      // Coerce -0 to +0.
      family = options.family + 0;
    }
    if (options?.all != null) {
      validateBoolean(options.all, 'options.all');
      all = options.all;
    }
    if (options?.verbatim != null) {
      validateBoolean(options.verbatim, 'options.verbatim');
      dnsOrder = options.verbatim ? 'verbatim' : 'ipv4first';
    }
    if (options?.order != null) {
      validateOneOf(options.order, 'options.order', validDnsOrders);
      dnsOrder = options.order;
    }
  }

  return createLookupPromise(family, hostname, all, hints, dnsOrder);
}


function onlookupservice(err, hostname, service) {