Add opacity control for Leaflet layers.
Check out the demo !
Like Leaflet Layers Control
var baseMaps = {
"Minimal": minimal,
"Night View": midnight
};
var overlayMaps = {
"Motorways": motorways,
"Cities": cities
};
L.control.layers(baseMaps, overlayMaps).addTo(map);
Stéphane Benchimol