Document: timeline property

The timeline readonly property of the Document interface represents the default timeline of the current document. This timeline is a special instance of DocumentTimeline.

This timeline is unique to each document and persists for the lifetime of the document including calls to Document.open().

This timeline expresses the time in milliseconds since Performance.timeOrigin. Prior to the time origin, the timeline is inactive, and its currentTime is null.

Note: A document timeline that is associated with a non-active document (a Document not associated with a Window, <iframe>, or <frame>) is also considered to be inactive.