Source

<!DOCTYPE html>
<html>
  <!--
    requires the following npm packages:

    * leaflet
  -->
  <head>
    <title>A Simple Map</title>
    <meta charset="utf-8" />
    <script src="../../node_modules/leaflet/dist/leaflet.js"></script>
    <link rel="stylesheet" href="../../node_modules/leaflet/dist/leaflet.css"/>
  </head>
  <body>
    <div id='mapDiv' style='width: 800px; height: 600px'></div>
    <script>
      var latLon = [53.56250, 9.95982];
      var zoom = 18;

      var osmLayer = L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', 
                                 {attribution: 'Map data &copy; OpenStreetMap contributors'});

      var myMap = L.map('mapDiv', { layers: osmLayer}).setView(latLon, zoom);
    </script>
  </body>
</html>