function main(projectId, zone, instanceName) {
  // [START compute_instances_get_hostname]
  /**
   * TODO(developer): Uncomment and replace these variables before running the sample.
   */
  // const projectId = 'YOUR_PROJECT_ID';
  // const zone = 'europe-central2-b'
  // const instanceName = 'YOUR_INSTANCE_NAME'

  const compute = require('@google-cloud/compute');

  async function getInstanceHostname() {
    const instancesClient = new compute.InstancesClient();

    const [instance] = await instancesClient.get({
      project: projectId,
      zone,
      instance: instanceName,
    });
    // If a custom hostname is not set, the output for instance.hostname will be undefined
    console.log(`Instance ${instanceName} has hostname: ${instance.hostname}`);
  }

  getInstanceHostname();
  // [END compute_instances_get_hostname]
}
Prints the hostname of the Google Cloud VM instance.

@param {string} projectId - ID of the project in which you want to get the VM instance hostname.
@param {string} zone - Name of the zone your instance belongs to, for example: us-west3-b.
@param {string} instanceName - Name of the new VM instance.