An example using topojson.mesh() to distinguish between municipal (white) and provincial (black) boundaries.
An arc is stroked as a provincial boundary (black) if
- the arc is shared by two geometry objects (i.e.
a !== b
) AND they do not have the same province name (i.e.a.properties.provincie !== b.properties.provincie
) - the arc is only used by a single geometry (i.e.
a === b
). This is the case for all external, national boundaries.