MozNFC is the top level API for operating in NFC Reader/Writer mode, NFC P2P mode and NFC Card Emulation mode.
The getNFCPeer() method of the MozNFC interface returns a Peer to Peer DOM object (MozNFCPeer) that can be used to transfer data to another NFC-enabled device.
The getNFCTag() method of the MozNFC interface returns an NDEF tag interface (MozNFCTag object) used to interact with NFC Tags.
The onpeerlost event handler of the MozNFC interface handles the peerlost event, which is fired when the MozNFCPeer object received in MozNFC.onpeerready  is no longer available or not in proximinty (e.g. the peer device moves out of range.).
The onpeerready event handler of the MozNFC interface handles the peerready event, which fires when a suitable peer (an NFC-enabled device) comes into range of the device your NFC application is running on.