Merge pull request #1 from morikuni/add-tile-layer

Support multiple layers

template.go

@@ -27,9 +27,19 @@ const htmlTemplate = `
         center: [0, 0],
         zoom: 1,
       });
-      L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
-          attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
+      // tiles are copied from: https://leaflet-extras.github.io/leaflet-providers/preview/
+	  const Esri_WorldStreetMap = L.tileLayer('https://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer/tile/{z}/{y}/{x}', {
+	    attribution: 'Tiles &copy; Esri &mdash; Source: Esri, DeLorme, NAVTEQ, USGS, Intermap, iPC, NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand), TomTom, 2012'
       }).addTo(map);
+      const OpenStreetMap_Mapnik = L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
+        maxZoom: 19,
+        attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
+      });
+      const layers = {
+     	"Esri": Esri_WorldStreetMap, 
+     	"OpenStreetMap": OpenStreetMap_Mapnik, 
+      }
+      L.control.layers(layers).addTo(map);
       map.attributionControl.addAttribution('&copy; <a href="https://github.com/morikuni/go-geoplot">go-geoplot</a> by <a href="https://github.com/morikuni">morikuni</a>');
       {{ range .lines }}
       {{- .}}