Simple control to show a gif loader to the center of the map
demo:
opengeo.tech/maps/leaflet-loader
...
const controlLoader = L.control.loader().addTo(map);
$.ajaxSetup({
beforeSend: e => {
controlLoader.show()
},
complete: e => {
controlLoader.hide()
}
});
const geoLayer = L.geoJson([]).addTo(map);
$.getJSON(`mygeojson.json`, geoj => {
geoLayer.addData(geoj);
});