Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
Obsolete since Gecko 51 (Firefox 51 / Thunderbird 51 / SeaMonkey 2.48)
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.
Summary
Indicates whether or not the social media provider's content sidebar is currently visible.
Syntax
var visible = navigator.MozSocial.isVisible
On return, visible is true if the sidebar is currently visible; otherwise it's false.
Specification
Not part of any specification.