Leaflet Swipe between OpenCycleMap and Stamen Watercolor

<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>Swipe between layers</title>
<meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' />
<script src='https://cdnjs.cloudflare.com/ajax/libs/leaflet/0.7.3/leaflet.min.js'></script>
<link rel="stylesheet" href="https://cdn.leafletjs.com/leaflet-0.7.3/leaflet.css" />
<style>
  body { margin:0; padding:0; }
  #map { position:absolute; top:0; bottom:0; width:100%; }
</style>
</head>
<body>

var overlay = L.tileLayer('https://a.tile.thunderforest.com/cycle/{z}/{x}/{y}.png').addTo(map);
  var range = document.getElementById('range');

function clip() {
    var nw = map.containerPointToLayerPoint([0, 0]),
        se = map.containerPointToLayerPoint(map.getSize()),
        clipX = nw.x + (se.x - nw.x) * range.value;

overlay.getContainer().style.clip = 'rect(' + [nw.y, clipX, se.y, nw.x].join('px,') + 'px)';
  }

range['oninput' in range ? 'oninput' : 'onchange'] = clip;
  map.on('move', clip);
  map.setView([41.38506, 2.17340], 15);

clip();
</script>

</body>
</html>

Modified http://cdn.leafletjs.com/leaflet-0.7.3/leaflet.js to a secure url

https://cdn.leafletjs.com/leaflet-0.7.3/leaflet.js