NodeWebSocket declaration issue (nodejs project)

[szymonlesisz]

You want to:

• report a bug
• request a feature

Current behaviour

According to this pice of code:
https://github.com/socketio/engine.io-client/blob/master/lib/transports/websocket.js#L14-L22
NodeWebSocket will be required ONLY if global variables self and WebSocket are not defined.

Steps to reproduce (if the current behaviour is a bug)

node.js:

global.self = {}; 
// - declaring global.self before requiring `websocket.js` will end up with timeout, because of mentioned block of code. 
// It will try to set BrowserWebSocket = self.WebSocket || self.MozWebSocket; and fail. 
// now both BrowserWebSocket and NodeWebSocket are undefined

const SocketIO = require('socket.io-client');
const socket = SocketIO('http://localhost', {
        transports: ['websocket'],
        timeout: 5000,
        reconnection: false,
});
socket.on('connect', function () {
        console.log('WS connected');
});
socket.on('connect_error', function (e) {
        console.log('WS error', e);
});

Expected behaviour

NodeWebSocket should not be undefined

Setup

• OS: any
• nodejs
• engine.io version: current

Other information (e.g. stacktraces, related issues, suggestions how to fix)

Mentioned condition is not valid, there should be additional check if BrowserWebSocket is set OR there should better nodejs environment detection (i think typeof self !== 'undefined is not enough)