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.
 The priority field's value is set from the candidateInfo options object passed to the RTCIceCandidate() constructor. You can't specify the value of priority directly in the options object, but its value is automatically extracted from the object's candidate a-line, if it's formatted properly. 
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 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 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 | 
|---|
| WebRTC 1.0: Real-Time Communication Between Browsers (WebRTC 1.0) # dom-rtcicecandidate-priority  | 
Browser compatibility
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
priority | 
74  | 
79  | 
No  | 
No  | 
62  | 
14.1  | 
74  | 
74  | 
No  | 
53  | 
14.5  | 
11.0  | 
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    https://developer.mozilla.org/en-US/docs/Web/API/RTCIceCandidate/priority