The RTCIceCandidate interface's read-only type specifies the type of candidate the object represents.

The type field's value is set from the candidateInfo options object passed to the RTCIceCandidate() constructor. You can't specify the value of type directly in the options object, but its value is automatically extracted from the object's candidate a-line (the cand-type field), if it's formatted properly.

A string whose value is one of those defined below. These candidate types are listed in order of priority; the higher in the list they are, the more efficient they are.

host

The candidate is a host candidate, whose IP address as specified in the RTCIceCandidate.address property is in fact the true address of the remote peer.

srflx

The candidate is a server reflexive candidate; the ip and port are a binding allocated by a NAT for an agent when it sent a packet through the NAT to a server. They can be learned by the STUN server and TURN server to represent the candidate's peer anonymously.

prflx

The candidate is a peer reflexive candidate; the ip and port are a binding allocated by a NAT when it sent a STUN request to represent the candidate's peer anonymously.

relay

The candidate is a relay candidate, obtained from a TURN server. The relay candidate's IP address is an address the TURN server uses to forward the media between the two peers.

If type is null, that information was missing from the candidate's a-line, which will cause RTCPeerConnection.addIceCandidate() to throw an OperationError exception.

In this example, the candidate's type is used to present a modified user interface for host candidates (those where the ip refers directly to the remote peer, rather than an intermediary).

if (candidate.type === "host") {
  showHostControls();
} else {
  hideHostControls();
}

• WebRTC API
• Introduction to WebRTC protocols
• WebRTC connectivity
• RTCIceCandidate.tcpType