leaflet random lat lng in map
function getRandomLatLng(map) {
var bounds = map.getBounds(),
southWest = bounds.getSouthWest(),
northEast = bounds.getNorthEast(),
lngSpan = northEast.lng - southWest.lng,
latSpan = northEast.lat - southWest.lat;
return new L.LatLng(
southWest.lat + latSpan * Math.random(),
southWest.lng + lngSpan * Math.random());
}