If we're proposing a markup-based map widget, it would be nice to have examples of existing tools that use an element and attribute API for embedding and customizing maps.

There is of course the community group's own custom element proposal, but it's circular logic to use it as an example!

I've found a few custom elements that are wrappers for the various major maps APIs, but not sure which ones would make a good reference:

• official Google google-map component; looks like it was comprehensive (child elements for markers & so on) but the demos are all broken
• simpler good-map that uses Google
• leaflet-map, another basic map
• mapbox-gl looks fairly comprehensive