The BatteryManager interface provides ways to get information about the system's battery charge level.
The navigator.mozAudioChannelManager object provides access to the mozAudioChannelManager interface, which is used to manage your Firefox OS device's audio channels, including setting what channel's volume to affect when the volume buttons are pressed inside a particular app.
The getBattery() method provides information about the system's battery, returns a battery promise, which is resolved in a BatteryManager object providing also some new events you can handle to monitor the battery status.. This implements the Battery Status API; see that documentation for additional details, a guide to using the API, and sample code.
The navigator.mozAudioChannelManager object provides access to the mozAudioChannelManager interface, which is used to manage your Firefox OS device's audio channels, including setting what channel's volume to affect when the volume buttons are pressed inside a particular app.
The mozNfc property returns a MozNFC object that can be used to access Firefox OS's NFC functionality: Near Field Communication (NFC) is a short range radio technology used to exchange data and tags between mobile devices by tapping them together or moving them close to each other.