javascript - What does peer_connection.onicecandidate() function do?what is an ice_event? -

i having difficulty in understanding puropse of onicecandidate function. how ice candidates helps in establishing peer connection.and sends ice candidates first?

• under hood, webrtc gather local candidate depending on available network connections, , list of ice servers passed through js api.
• once ice candidate ready, provided js layer through onicecandidate api.
• if you're using trickle ice, can send candidate right away through signaling path remote peer. otherwise, wait last (null) candidate, order them priority, add them offer/answer sdp, , send offer/answer through signaling path. done automatically browser.
• you might @ handshake specifications here: https://tools.ietf.org/html/draft-ietf-rtcweb-jsep-09