<button id="find-me">Show my location</button><br>
<p id="status"></p>
<a id="map-link" target="_blank"></a>
<script>

function geoFindMe() {

  const status = document.querySelector('#status');
  const mapLink = document.querySelector('#map-link');

  mapLink.href = '';
  mapLink.textContent = '';

  function success(position) {
    const latitude  = position.coords.latitude;
    const longitude = position.coords.longitude;

    status.textContent = '';
    mapLink.href = `https://www.openstreetmap.org/#map=18/${latitude}/${longitude}`;
    mapLink.textContent = `Latitude: ${latitude} °, Longitude: ${longitude} °`;
  }

  function error() {
    status.textContent = 'Unable to retrieve your location';
  }

  if(!navigator.geolocation) {
    status.textContent = 'Geolocation is not supported by your browser';
  } else {
    status.textContent = 'Locating…';
    navigator.geolocation.getCurrentPosition(success, error);
  }

}

document.querySelector('#find-me').addEventListener('click', geoFindMe);

</script>

Beispiel

https://dev.merlincom.ch/entwicklung/geolocation/