Replayer
The replayer is the component that turns a stored event stream back into a watchable session: it rebuilds the initial full snapshot, then applies incremental events on a timeline with play, pause, seek, and speed controls. In rrweb it ships as the `Replayer` class, with `rrweb-player` adding a ready-made UI.
How it works
new Replayer(events) deserializes the first full snapshot into a sandboxed iframe and schedules the remaining events by timestamp. Seeking jumps to the nearest prior full snapshot and applies events forward at maximum speed until reaching the target time, which is why checkout frequency governs seek latency. Options cover playback speed, live mode for in-progress sessions, and canvas replay. rrweb-player wraps this with a controller bar, timeline, and skipInactive handling, and is what most teams embed.
Where you encounter it
In every replay UI, and increasingly in headless form: pipelines replay sessions server-side to extract screenshots, generate videos, or feed reconstructed states to analysis models.