The Web Performance Working Group has published the Page Visibility Level 2 as a W3C Candidate Recommendation Snapshot. This specification defines a means to programmatically determine the visibility state of a document. This can aid in the development of resource efficient web applications.
The document was previously published as a Proposed Recommendation and now returns to Candidate Recommendation status to allow better integration with the HTML specification. Further, this snapshot has been updated so that dependent specifications can better integrate with its various defined concepts and algorithms.
The Working Group welcomes comments via the GitHub repository issues by 18 June 2021.