let mapOptions = {
center:[34.2121525, 108.8284321],
zoom:10
}
let map = new L.map('map' , mapOptions);
let layer = new L.TileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png');
map.addLayer(layer);
let marker = new L.Marker([34.2121525, 108.8284321]);
marker.addTo(map);