Widget:Leaflet

<map id="map" style="width:100%; height:600px;"></map>

<script> (function(){

   function debug(msg) {
       var dbg=document.getElementById("debug");
       if(dbg) dbg.textContent += "\n" + msg;
   }

   var rawEl = document.getElementById("smw-data");
   if (!rawEl) {
       debug("FEHLER: smw-data nicht gefunden!");
       return;
   }

   var raw = rawEl.textContent.trim();
   debug("ROHDATEN:\n" + raw);

   var schools=[];
   try {
       schools = JSON.parse(raw);
       debug("JSON erfolgreich geparst ("+schools.length+" Einträge)");
   } catch(e) {
       debug("JSON PARSE FEHLER: "+e);
       return;
   }

   var map = L.map("map").setView([50.94, 6.97], 12);
   L.tileLayer("https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png", {
       maxZoom:19
   }).addTo(map);

   var markerGroup = L.markerClusterGroup();

   schools.forEach(function(s){
       if(!s.coords) return;
       var parts=s.coords.split(",");
       if(parts.length !== 2) return;

       var lat=parseFloat(parts[0]);
       var lon=parseFloat(parts[1]);
       if(isNaN(lat)||isNaN(lon)) return;

       var marker=L.marker([lat,lon]).bindPopup(
           ""+(s.name||"Unbekannt")+"
"+
           (s.type||"")
       );
       markerGroup.addLayer(marker);
   });

   map.addLayer(markerGroup);

})(); </script>