var osm = L.tileLayer('https://{s}.basemaps.cartocdn.com/rastertiles/voyager/{z}/{x}/{y}{r}.png', {
	attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors &copy; <a href="https://carto.com/attributions">CARTO</a>',
	subdomains: 'abcd',
	maxZoom: 28
});

mapLink =   '<a href="http://www.esri.com/">Esri</a>';
wholink =   'i-cubed, USDA, USGS, AEX, GeoEye, Getmapping, Aerogrid, IGN, IGP, UPR-EGP, and\ the GIS User Community';
var sat = L.tileLayer(
  'http://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/ti\le/{z}/{y}/{x}', {
  attribution: '&copy; '+mapLink+', '+wholink,
  maxZoom: 28,
  });

var mapa = L.tileLayer('https://{s}.tile.openstreetmap.fr/hot/{z}/{x}/{y}.png', {
	maxZoom: 28,
	attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors, Tiles style by <a href="https://www.hotosm.org/" target="_blank">Humanitarian OpenStreetMap Team</a> hosted by <a href="https://openstreetmap.fr/" target="_blank">OpenStreetMap France</a>'
});

var google = L.tileLayer('https://mt1.google.com/vt/lyrs=r&x={x}&y={y}&z={z}', {attribution: '<a href="https://www.google.es/maps/preview">Google Maps</a>'});

var pnoa = L.tileLayer.wms("http://www.ign.es/wms-inspire/pnoa-ma?SERVICE=WMS&", {
	   layers: "OI.OrthoimageCoverage",//nombre de la capa (ver get capabilities)
	   format: 'image/jpeg',
	   transparent: true,
	   version: '1.3.0',//wms version (ver get capabilities)
	   maxZoom: 28,
	   attribution: "PNOA WMS. Cedido por © Instituto Geográfico Nacional de España"
	});

var googleSat = L.tileLayer('http://{s}.google.com/vt/lyrs=s&x={x}&y={y}&z={z}',{
    maxZoom: 25,
    subdomains:['mt0','mt1','mt2','mt3']
});

var pnoa2 = L.tileLayer.wms("https://www.ign.es/wmts/pnoa-ma?layer=OI.OrthoimageCoverage&style=default&tilematrixset=GoogleMapsCompatible&Service=WMTS&Request=GetTile&Version=1.0.0&Format=image/jpeg&TileMatrix={z}&TileCol={y}&TileRow={x}", {
	   service:'',
	   request:'',
	   srs:'',
	   transparent: true,
	   maxZoom: 28,
	   attribution: "PNOA WMTS. Cedido por © Instituto Geográfico Nacional de España"
	});

<!--
var stamen = L.tileLayer('https://stamen-tiles-{s}.a.ssl.fastly.net/toner/{z}/{x}/{y}.png',{
	maxZoom: 22,
	attribution: 'Map tiles by <a href="https://stamen.com">Stamen Design</a>, ' + '<a href="https://creativecommons.org/licenses/by/3.0">CC BY 3.0</a> | ' + 'Map data <a href="https://openstreetmap.org">OpenStreetMap</a>', 
	ext: 'jpg'});
-->
var alto_contraste = L.tileLayer('https://tiles.stadiamaps.com/tiles/alidade_smooth_dark/{z}/{x}/{y}{r}.png', {
	maxZoom: 20,
	attribution: '© <a href="https://stadiamaps.com/">Stadia Maps</a>, © <a href="https://openmaptiles.org/">OpenMapTiles</a> © <a href="http://openstreetmap.org">OpenStreetMap</a> contributors'
});
<!-- //let map = L.map('map',{preferCanvas:true}).setView([38.994426, -1.856176],13); -->

var baseMaps = {
	"OSM" : osm,
	<!-- "Calles" : mapa, -->
	"ESRI sat" : sat,
	"PNOA" : pnoa,
	<!-- "PNOA2" : pnoa2, -->
	<!-- "Contraste" : alto_contraste, -->
	"Google Street" : google,
	"Google Satellite" : googleSat,
	<!-- "Stamen" : stamen -->
};