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This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

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


var value = sessionDescription.type;
sessionDescription.type = value; 


The possible values are defined by an enum of type RTCSdpType.

The allowed values are those of an enum of type RTCSdpType:

  • "offer", the description is the initial proposal in an offer/answer exchange.
  • "answer", the description is the definitive choice in an offer/answer exchange.
  • "pranswer", the description is a provisional answer and may be changed when the definitive choice will be given.
  • "rollback", the description rolls back to offer/answer state to the last stable state.


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



Specification Status Comment
WebRTC 1.0: Real-time Communication Between Browsers
The definition of 'RTCSessionDescription.type' in that specification.
Working Draft Initial specification.

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) [1] (Yes) (Yes) [1] No support (Yes) ?
Feature Android Chrome for Android Edge Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support ? ? (Yes) ? No support ? ?

[1] Though this property is not prefixed, the interface it belongs to is.

See also

Document Tags and Contributors

 Contributors to this page: nils, abbycar, Sheppy, teoli
 Last updated by: nils,