Googla Maps API - Add a KML layer

google-add-kml.js

/* Add layer(s) from an online KML or KMZ file
 *
 * function: google.maps.KmlLayer
 * documentation: https://developers.google.com/maps/documentation/javascript/examples/layer-kml
 */
 
let kml = new google.maps.KmlLayer({
  url: 'http://example.com/layer1.kmz',
  preserveViewport: true // setting to true will prevent the map from zooming to this layer
});
kml.setMap( map );