Hi! We just removed serializers[1] from WebIDL and allowed editors to specify toJSON operations[2] directly instead (WebIDL treated toJSON as a reserved identifier up until now). To deal with common cases, we added a new [Default] extended attribute[3] which triggers the default toJSON operation[4] that behaves similarly to how serializers={attributes} or serializers={attributes, inherit} used to. All serializer-related productions were removed from the WebIDL grammar. In particular the following non-terminals: * Serializer * Serializer was also removed from the rhs expression of InterfaceMember. * SerializerRest * OperationRest * SerializationPattern * SerializationPatternMap * SerializationPatternList and the following terminals: * "serializer" in ArgumentNameKeyword. As usual, please feel free to reach out if anything needs clarification or if you have questions. Thanks! [1]: https://github.com/heycam/webidl/pull/323 [2]: https://heycam.github.io/webidl/#idl-tojson-operation [3]: https://heycam.github.io/webidl/#Default [4]]: https://heycam.github.io/webidl/#es-default-tojson