What does geometryLength param do?

[emacgillavry]

See:

• https://github.com/NieneB/webmapping_for_developers/blob/master/leaflet-part-4/index.html#L108
• https://github.com/NieneB/webmapping_for_developers/blob/master/mapbox-gl-js-part-2/index.html#L152

Not something that's part of the WFS spec?

It's also mentioned in the wiki: https://github.com/NieneB/webmapping_for_developers/wiki/Leaflet-part-4