OptionaldefaultWhether this track should be selected by default.
OptionalidOptional pre-assigned UUID. When omitted a new UUID is generated automatically.
OptionalkindThe kind of text track (subtitles, captions, etc.).
OptionallabelHuman-readable label for this track.
OptionalloadTrack load status *
OptionalrelationsInitial set of inter-track relations.
OptionalsourceData source backing this track.
OptionalsourceThe resolved file format of the source.
OptionalsrclangBCP 47 language tag (e.g. "en").
Construction arguments for text track instances.