====== adv.addDataChannel() ======
call.adv.addDataChannel() can be used to add a [[ixnx:wrtc:js:data_channel|data channel]] to a call.

The created data channel will be active until the call is ended. You can transmit data several times on it using [[ixnx:wrtc:js:api:call:adv.senddata|call.adv.sendData()]] without the need to reopen it again.

**Usually you do not explicitly need to call call.adv.addDataChannel()** as [[ixnx:wrtc:js:api:call:adv.senddata|call.adv.sendData()]] will call it if needed. You may however need to call call.adv.addDataChannel() if you want other constraints than the default {ordered: true} for the data channel.

===== Arguments =====
call.adv.addDataChannel(constraints)
  * constraints - [[https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/createDataChannel#RTCDataChannelInit_dictionary|constraints]] to use when creating the data channel. If missing default is {ordered: true}

===== Returns =====
Nothing.

===== Errors =====
If data channel is not supported [[ixnx:wrtc:js:api:wrtc:onerror|error 311]] will occur. Check **call.is("dataChannelSupport")** to avoid getting errors on browsers not supporting data channels.

===== Example =====
  if call.is("dataChannelSupport") {
    call.adv.addDataChannel({ordered:false});
    call.adv.sendData("HELLO");
  }

===== See also =====
[[ixnx:wrtc:js:api:call:adv.senddata|call.adv.sendData()]]

[[ixnx:wrtc:js:data_channel|data channels]]

[[ixnx:wrtc:js:api:call:is|call.is("dataChannelSupport")]]

[[ixnx:wrtc:js:api:wrtc:onerror|wrtc.onError()]]