Stating with Firefox 60 -- expected to be released in May 2018 -- websites won't be able to use Firefox to access data from sensors that provide proximity distances and ambient light information
. From a report: Firefox was allowing websites to access this data via the W3C Proximity and Ambient Light APIs. But at the start of the month, Mozilla engineers decided to disable access to these two APIs by default. The APIs won't be removed, but their status is now controlled by two Firefox flags that will ship disabled by default. This means users will have to manually enable the two flags before any website can use Firefox to extract proximity and ambient light data from the device's underlying sensors. The two flags will be available in Firefox's about:config settings page. The screenshot below shows the latest Firefox Nightly version, where the two flags are now disabled, while other sensor APIs are enabled.