The RTCIceCandidate interface's read-only priority property specifies the candidate's priority according to the remote peer; the higher this value is, the better the remote peer considers the candidate to be.

As is the case with most of RTCIceCandidate's properties, the value of priority is extracted from the candidate a-line string specified when creating the RTCIceCandidate. The a-line string is obtained either from the RTCIceCandidateInit property candidate or from an a-line string passed into RTCPeerConnection.addIceCandidate() instead of an RTCIceCandidate.


var priority = RTCIceCandidate.priority;


A long, unsigned integer value indicating the priority of the candidate according to the remote peer. The larger this value is, the more preferable the remote peer considers this candidate to be.

priority is initialized to null if it is not specified in the candidate, or if the candidate string can't be parsed properly.

Note: If priority is null, passing the candidate to addIceCandidate() will fail, throwing an OperationError exception. This applies only if the candidate implements the priority property.

Usage notes

Consider this SDP attribute line (a-line) which describes an ICE candidate:

a=candidate:4234997325 1 udp 2043278322 44323 typ host

The priority is the number after the protocol, so it's the fourth field in the candidate string. In this example, the priority is 2043278322.


This candidate examines the priority of the candidate and, if it's greater than the priority of a previously-seen candidate, remembers the candidate for later use.

var bestCandidate = {
  candidate: "",
  sdpMid: null,
  sdpMLineIndex: null,
  priority: 0

function handleCandidate(candidateString) {
  var candidate = new RTCIceCandidate(candidateString);

  if (candidate.priority > bestCandidate.priority) {
    bestCandidate = candidate;


WebRTC 1.0: Real-Time Communication Between Browsers (WebRTC 1.0)
# dom-rtcicecandidate-priority

Browser compatibility

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