Node.js和Socket.io-无法读取未定义的属性“ on”

Question

I have run into an error when establishing a websocket connection using socket.io and node.js. Here is my environment:

• OS: Windows 7
• Node: 6.9.2
• NPM: 4.0.5
• Packages:
  • "express": "^4.14.0"
  • "socket.io": "1.7.1"
  • "socket.io-client": "1.7.1"
  • "ws": "1.1.1"

When a websocket connection is attempted the following error is thrown:

TypeError: Cannot read property 'on' of undefined
    at PerMessageDeflate.decompress (C:\ng-project\node_modules\ws\lib\PerMessageDeflate.js:242:37)
    at Receiver.applyExtensions (C:\ng-project\node_modules\ws\lib\Receiver.js:362:54)
    at C:\ng-project\node_modules\ws\lib\Receiver.js:508:14
    at Receiver.flush (C:\ng-project\node_modules\ws\lib\Receiver.js:347:3)
    at Receiver.opcodes.1.finish (C:\ng-project\node_modules\ws\lib\Receiver.js:541:12)
    at Receiver.expectHandler (C:\ng-project\node_modules\ws\lib\Receiver.js:493:33)
    at Receiver.add (C:\ng-project\node_modules\ws\lib\Receiver.js:103:24)
    at Socket.realHandler (C:\ng-project\node_modules\ws\lib\WebSocket.js:825:20)
    at ZoneDelegate.invokeTask (C:\ng-project\node_modules\zone.js\dist\zone-node.js:265:35)
    at Zone.runTask (C:\ng-project\node_modules\zone.js\dist\zone-node.js:154:47)
    at Socket.ZoneTask.invoke (C:\ng-project\node_modules\zone.js\dist\zone-node.js:335:33)
    at emitOne (events.js:96:13)
    at Socket.emit (events.js:188:7)
    at readableAddChunk (_stream_readable.js:177:18)
    at Socket.Readable.push (_stream_readable.js:135:10)
    at TCP.onread (net.js:542:20)

Looking into the ws module I can see the line of code throwing the error:

this._inflate.on('error', onError).on('data', onData);

_inflate is a zlib InflateRaw instance created by zlib.createInflateRaw({...}) a few lines earlier. The problem is that the InflateRaw#on function returns undefined in my environment.

I have tried installing alternate versions of Node to work around this without any luck... Altering the ws package is not an acceptable workaround for me.

EDIT 1: Adding source code which throws the error.

io.on('connection', (socket) => {
  // Listen for verification subscription requests
  log.debug("Established socket connection " + socket.id);
  socket.on('verify subscribe', (msg) => {
    log.debug("Recieved 'verify subscribe' message: " + JSON.stringify(msg));
    // Do stuff....
  });
});

This code outputs the following log messages prior to the error:

[2016-12-30T19:08:09.219Z] DEBUG: Established socket connection -g9oZM6pEqpFyU_BAAAA
[2016-12-30T19:08:09.275Z] DEBUG: Recieved 'verify subscribe' message: {"token":"short-ish.token","authorization":"long.auth-token"}

Answer 1

This issue was discovered to be a bug with zone.js and has been fixed in later versions (>0.7.0). The issue is tracked on GitHub here: angular/zone.js#508 .

Answer 2

You io is not set yet. Make sure you have done

var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);

From the docs chat example - http://socket.io/get-started/chat/

If you don't setup io it will be undefined .

Also see: http://socket.io/docs/#

var app = require('http').createServer(handler)
var io = require('socket.io')(app);