I'm trying to display the position of the viewer through a marker.

var redIcon = new L.Icon({
  iconUrl: 'https://raw.githubusercontent.com/pointhi/leaflet-color-markers/master/img/marker-icon-2x-red.png',
  shadowUrl: 'https://cdnjs.cloudflare.com/ajax/libs/leaflet/0.7.7/images/marker-shadow.png',
  iconSize: [25, 41],
  iconAnchor: [12, 41],
  popupAnchor: [1, -34],
  shadowSize: [41, 41]
});
map.locate({setView: true, watch: true, maxZoom: 18});
function onLocationFound(e) {
    L.marker(e.latlng, {icon: redIcon}).addTo(map)
}

map.on('locationfound', onLocationFound);

It's clear that watch: true displays the marker, however it does not update each time, but it displays a new marker with a position change. That means, the map is now full of postion markers.

How can I show only one marker when changing my position.