OptionalcenterOptionalmapraw Leaflet L.Map options, passed straight to L.map(el, mapOptions).
Optionaltileoptions passed to L.tileLayer (e.g. attribution).
Optionaltilebasemap tile URL template; pass null to opt out of the default
OpenStreetMap tile layer (e.g. to add your own via L.tileLayer).
Optionalzoominitial zoom level; defaults to 5.
initial map center; defaults to the continental US.