onOpen method
void
onOpen()
Called upon transport considered open.
Implementation
void onOpen() {
readyState = 'open';
// sends an `open` packet
transport.sid = id;
sendPacket('open',
data: json.encode({
'sid': id,
'upgrades': getAvailableUpgrades(),
'pingInterval': server.pingInterval,
'pingTimeout': server.pingTimeout
}));
emit('open');
setPingTimeout();
}