I'm looking into using Leaflet to make maps and place markers in an internal application (i.e. not a web-site, but a simple desktop application), but I'm wondering which data is sent and which is not. Do the following command send any data or is it only plotted locally?
marker = L.marker([51.5, -0.09]).addTo(mymap);
It's all local (I use leaflet offline all the time). If you want to check the source code for markers and look for yourself, feel free to check it out here