visibilityState
The Document.visibilityState read-only property returns the visibility of the document. It can be used to check whether the document is in the background or in a minimized window, or is otherwise not visible to the user.
The Document.visibilityState read-only property returns the visibility of the document. It can be used to check whether the document is in the background or in a minimized window, or is otherwise not visible to the user.