Web/API/RTCIceCandidate/priority

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.

Syntax

var priority = RTCIceCandidate.priority;

Value

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 propertly.

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 192.168.0.56 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.

Example

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;
  }
}

Specifications

Specification	Status	Comment
WebRTC 1.0: Real-time Communication Between BrowsersThe definition of 'RTCIceCandidate.priority' in that specification.	Candidate Recommendation	Initial definition.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`priority`	Chrome Full support 74	Edge Full support ≤18	Firefox No support No	IE No support No	Opera No support No	Safari ?	WebView Android Full support 74	Chrome Android Full support 74	Firefox Android No support No	Opera Android No support No	Safari iOS ?	Samsung Internet Android Full support 11.0

Legend

Full support: Full support
No support: No support
Compatibility unknown: Compatibility unknown

RTCIceCandidate.priority by Mozilla Contributors is licensed under CC-BY-SA 2.5.