People are so malevolent sometimes. Something as innocuous as battery
First, we report that we have found a wide misuse and abuse
of Battery Status API. We provide evidence that the
API is used for purposes it was not designed to. We found
16 third-party scripts using the API in tracking, 11 of them is using
the API for fingerprinting purposes.
So the Battery API is being removed from mobile browsers,
an unprecedented move in the history of the web; for
the first time, an entire API has been purged citing privacy concerns.
Read the whole story here: Battery Status Not Included: Assessing
Privacy in W3C Web Standards