The ready state of the player, represented by a value from the following list:
0 (HAVE_NOTHING): The player has no information about the duration of its source.
1 (HAVE_METADATA): The player has information about the duration of its source.
2 (HAVE_CURRENT_DATA): The player has its current frame in its buffer.
3 (HAVE_FUTURE_DATA): The player has enough data for immediate playback.
4 (HAVE_ENOUGH_DATA): The player has enough data for continuous playback.
- See the [HTML Media Specification](https://html.spec.whatwg.org/multipage/media.html#ready-states)