RTCSessionDescription: type property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.

The property RTCSessionDescription.type is a read-only string value which describes the description's type.

const value = sessionDescription.type
sessionDescription.type = value

The possible values are:

"answer": The SDP contained in the sdp property is the definitive choice in the exchange. In other words, this session description describes the agreed-upon configuration, and is being sent to finalize negotiation.
"offer": The session description object describes the initial proposal in an offer/answer exchange. The session negotiation process begins with an offer being sent from the caller to the callee.
"pranswer": The session description object describes a provisional answer; that is, a response to a previous offer that is not the final answer. It is usually employed by legacy hardware.
"rollback": This special type with an empty session description is used to roll back to the previous stable state.

// The remote description has been set previously on pc, a RTCPeerConnection

alert(pc.remoteDescription.type);

Specification
WebRTC: Real-Time Communication in Browsers # dom-rtcsessiondescription-type

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