When all you need to do for "Node.js compatibility" is return 0...

return-0.md

When all you need to do for compatibility is return 0...

Testing @fails-components/webtransport in node, deno, and bun, when the code was written exclusively for Node.js, depending on Node.js Addon has been interesting this.socketInt.getSendQueueCount is undefined in transports/http3-quiche/lib/socket.js #409 If this.socketInt.getSendQueueCount is undefined define function that returns 0; support Deno #412.

Deno throws

DENO_COMPAT=1 deno -A wt-server.js
WebTransport server started
terminate called after throwing an instance of 'Napi::Error'
  what():  this.socketInt.getSendQueueCount is not a function
Aborted

DEBUG=webtransport* DENO_COMPAT=1 deno -A wt-client.js
  webtransport:native(116896) load webtransport binary: ./webtransport.node +0ms
terminate called after throwing an instance of 'Napi::Error'
  what():  this.socketInt.getSendQueueCount is not a function
Aborted

So, what the hell does this.socketInt.getSendQueueCount do?

That function is referenced twice in the source code, in webtransport/transports/http3-quiche/lib/socket.js

const blocked = this.socketInt.getSendQueueCount() > 0
// ...
     this.socketInt.getSendQueueCount() === 0 && 
// ...

All I got was 0s, ending with a Segmentation fault.

DENO_COMPAT=1 DEBUG=webtransport* deno -A wt-client.js
  webtransport:native(34516) load webtransport binary: ./webtransport.node +0ms
sendPacket false 0
# ...
sendPacket true 0
Segmentation fault

A little poking around... Bun just returns 0 in src/js/node/dgram.ts

Socket.prototype.getSendQueueCount = function () {
  return 0;
  // return this[kStateSymbol].handle.getSendQueueCount();
};

Voila, Deno works, is "Node.js compatible" - as server and client

this.socketInt = createSocket({
  type: result.family === 4 ? "udp4" : "udp6",
  ipv6Only: this.forceIpv6
});
if (!this.socketInt.getSendQueueCount) {
  this.socketInt.getSendQueueCount = function() { return 0 }
}

DEBUG=webtransport* DENO_COMPAT=1 deno -A wt-server.js
  webtransport:native(117029) load webtransport binary: ./webtransport.node +0ms
WebTransport server started
(node:117029) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.
Promise { <pending> }
4 20971520
WebTransport readable closed
WebTransport writable closed
  webtransport:http3wtstream(117029) callback streamFinal +0ms
  webtransport:http3wtstream(117029) callback streamFinal +20ms
  webtransport:httpwtsession(117029) onClose +0ms
Stream 0
Session done
Clients 0
#...

DEBUG=webtransport* DENO_COMPAT=1 deno -A wt-client.js
  webtransport:native(117067) load webtransport binary: ./webtransport.node +0ms
(node:117067) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.
WebTransport client ready
{ outgoingTotalLength: 20971520 }
Outgoing total length 20971520 written.
  webtransport:http3wtstream(117067) callback streamFinal +0ms
  webtransport:http3wtstream(117067) callback streamFinal +8ms
  webtransport:httpwtsession(117067) closeinfo { closeCode: 4999, reason: 'Done streaming.' } +0ms
  webtransport:http3wtstream(117067) callback stopSending +7ms
  webtransport:http3wtstream(117067) callback resetStream +1ms
  webtransport:httpwtsession(117067) onClose +5ms
{ closeCode: 4999, reason: "Done streaming." }