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• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

A negotiationneeded event is sent to the RTCPeerConnection when negotiation of the connection through the signaling channel is required. This occurs both during the initial setup of the connection as well as any time a change to the communication environment requires reconfiguring the connection.

冒泡	No
可取消	No
接口	事件
事件处理程序特性	RTCPeerConnection.onnegotiationneeded

negotiationneeded event is first dispatched to the RTCPeerConnection when media is first added to the connection. This starts the process of ICE negotiation by instructing your code to begin exchanging ICE candidates through the signaling server. See Signaling transaction flow in Signaling and video calling for a description of the signaling process that begins with a negotiationneeded 事件。

范例

In this example, we use addEventListener() to create an event handler for negotiationneeded . Its role is to create an SDP offer and send it through the signaling channel to the remote peer.

pc.addEventListener("negotiationneeded", ev => {
  pc.createOffer()
  .then(offer => return pc.setLocalDescription(offer))
  .then(() => sendSignalingMessage({
    type: "video-offer",
    sdp: pc.localDescription
  }))
  .catch(err => {
    /* handle error */
  );
}, false);
					

After creating the offer, the local end is configured by calling RTCPeerConnection.setLocalDescription() ; then a signaling message is created and sent to the remote peer through the signaling server, to share that offer with the other peer. The other peer should recognize this message and follow up by creating its own RTCPeerConnection , setting the remote description with setRemoteDescription() , and then creating an answer to send back to the offering peer.

You can also set an event handler for the negotiationneeded event by assigning the event handler function to the RTCPeerConnection.onnegotiationneeded 特性：

pc.onnegotiationneeded = ev => {
  pc.createOffer()
  .then(offer => return pc.setLocalDescription(offer))
  .then(() => sendSignalingMessage({
    type: "video-offer",
    sdp: pc.localDescription
  }))
  .catch(err => {
    /* handle error */
  );
};
					

For a more detailed example, see Starting negotiation in Signaling and video calling .

规范

规范	状态	注释
WebRTC 1.0: Real-time Communication Between Browsers The definition of 'negotiationneeded' in that specification.	候选推荐

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
negotiationneeded event	Chrome 24	Edge 15	Firefox 22	IE No	Opera 43	Safari 11	WebView Android Yes	Chrome Android Yes	Firefox Android 44	Opera Android 43	Safari iOS ?	Samsung Internet Android 6.0

图例

完整支持

完整支持

不支持

不支持

兼容性未知 ?

兼容性未知

另请参阅

• WebRTC API
• Signaling and video calling
• Lifetime of a WebRTC session
• WebRTC connectivity
• Introduction to WebRTC protocols

元数据

• 最后修改： Jan 25, 2020

相关话题

1. WebRTC API
2. RTCPeerConnection
3. 构造函数

   1. RTCPeerConnection()
4. 特性

   1. canTrickleIceCandidates
   2. connectionState
   3. currentLocalDescription
   4. currentRemoteDescription
   5. getDefaultIceServers()
   6. iceConnectionState
   7. iceGatheringState
   8. localDescription
   9. onaddstream
   10. onconnectionstatechange
   11. ondatachannel
   12. onicecandidate
   13. oniceconnectionstatechange
   14. onicegatheringstatechange
   15. onidentityresult
   16. onidpassertionerror
   17. onidpvalidationerror
   18. onnegotiationneeded
   19. onpeeridentity
   20. onremovestream
   21. onsignalingstatechange
   22. ontrack
   23. peerIdentity
   24. pendingLocalDescription
   25. pendingRemoteDescription
   26. remoteDescription
   27. sctp
   28. signalingState
5. 方法

   1. addIceCandidate()
   2. addStream()
   3. addTrack()
   4. close()
   5. createAnswer()
   6. createDataChannel()
   7. createOffer()
   8. generateCertificate()
   9. getConfiguration()
   10. getIdentityAssertion()
   11. getReceivers()
   12. getSenders()
   13. getStats()
   14. getStreamById()
   15. getTransceivers()
   16. removeStream()
   17. removeTrack()
   18. restartIce()
   19. setConfiguration()
   20. setIdentityProvider()
   21. setLocalDescription()
   22. setRemoteDescription()
6. 事件

   1. addstream
   2. identityresult
   3. negotiationneeded
   4. removestream
   5. signalingstatechange
7. 继承：

   1. EventTarget
8. Related pages for WebRTC

   1. MediaDevices.getUserMedia()
   2. Navigator.mediaDevices
   3. RTCCertificate
   4. RTCDTMFSender
   5. RTCDTMFToneChangeEvent
   6. RTCDataChannel
   7. RTCDataChannelEvent
   8. RTCDtlsTransport
   9. RTCErrorEvent
   10. RTCIceCandidate
   11. RTCIceTransport
   12. RTCPeerConnectionIceErrorEvent
   13. RTCPeerConnectionIceEvent
   14. RTCRtpReceiver
   15. RTCRtpSender
   16. RTCRtpTransceiver
   17. RTCSctpTransport
   18. RTCSessionDescription
   19. RTCStatsEvent
   20. RTCStatsReport
   21. RTCTrackEvent