files/en-us/web/api/document/timeline/index.md
{{ APIRef("Web Animations") }}
The timeline readonly property of the {{domxref("Document")}} interface represents the default timeline of the current document. This timeline is a special instance of {{domxref("DocumentTimeline")}}.
This timeline is unique to each document and persists for the lifetime of the document including calls to {{domxref("Document.open()")}}.
This timeline expresses the time in milliseconds since {{domxref("Performance.timeOrigin")}}.
Prior to the time origin, the timeline is inactive, and its {{domxref("AnimationTimeline.currentTime","currentTime")}} is null.
[!NOTE] A document timeline that is associated with a non-active document (a {{domxref("Document")}} not associated with a {{domxref("Window")}}, {{htmlelement("iframe")}}, or {{htmlelement("frame")}}) is also considered to be inactive.
A {{domxref("DocumentTimeline")}} object.
{{Specifications}}
{{Compat}}