Optional ReadonlynodeThe node's subclass state, written to SceneNodeDocument.data and handed back verbatim to InstantiateSceneOptions.nodeFactory (2026-08-06).
Return undefined — as this option does for every node when it is omitted
— and the node carries no data at all, so a document written without it
is byte-identical to one written before the field existed. Anything else
must be representable JSON; validateSceneDocument refuses the rest,
naming the node.
The pair with SerializeSceneOptions.nodeTypeOf: nodeTypeOf says
what class the node was, nodeDataOf says what state it held, and the
factory needs both to rebuild it.
Optional ReadonlynodeThe document type for a node this package has no name for — an
application's own Node subclass. Returning undefined falls back to the
built-in Scene / Group names, and a node with neither is a FourError.
Optional ReadonlyunknownWhat to do with a component whose type has no registered serializer (2026-08-06, A-15).
"throw" (the default) refuses the save: an unserializable component is
state that would be gone after the round trip, and a save that quietly
loses state is worse than one that fails. "skip" drops it — the right
choice for a writer that deliberately carries the hierarchy only, and the
reason the choice is the caller's.
The mirror of InstantiateSceneOptions.unknownComponents, same spelling and same default, so a program that has to be lenient says so once on each side rather than discovering the asymmetry.
Options for serializeScene.