This article is in need of a technical review.
This feature is not on a current W3C standards track, but it is supported on the Firefox OS platform. Although implementations may change in the future and it is not supported widely across browsers, it is suitable for use in code dedicated to Firefox OS apps.
linkSpeed property value provides the current speed of the connection in
var speed = instanceOfMozWifiConnectionInfoEvent.linkSpeed
Not part of any specification.