Once you have connected to the web page as a callee, and the caller's browser has initiated the JSEP offer/answer process, you will receive a new_description signal. We then call peer_connect.setRemoteDescription() to set this as the remote description, and if this description is really an offer, then we call peer_connection.createAnswer() to send back a response. Just like in the code snippet for the caller, we use the new_description_created() function to set this answer as our local description, and then serialize it into a new_description signal that is then sent back to the caller:
// handle signals as a callee
function callee_signal_handler(event) {
...
} else if (signal.type === "new_description") {
peer_connection.setRemoteDescription(
new rtc_session_description(signal.sdp),
function () {
if (peer_connection.remoteDescription.type == "offer") {
peer_connection.createAnswer(new_description_created, log_error...