Nodejs Websocket connection in an ES6 class - node.js

Question

I am not sure if this is the correct way to implement a websocket connection in NodeJS, but the problem I am having is not with WebSockets but with class variables.
This is my WebSocketClass:
class WebSocketCalss {
constructor ( httpserver )
{
console.log("Initializing WebSocketCalss");
this.httpServer = httpserver;
this.connection = null;
this.client = null;
this.initializeWebSocket();
}
initializeWebSocket()
{
var WebSocketServer = require('websocket').server;
var wsServer = new WebSocketServer({
httpServer: this.httpServer
});
wsServer.on('request', function(request) {
console.log((new Date()) + ' Connection from origin ' + request.origin + '.');
this.connection = request.accept(null, request.origin);
console.log((new Date()) + ' Connection accepted.');
this.connection.sendUTF(JSON.stringify({ type: "history", data: "data"} ));
var t = 0;
/* ---- Client ---- */
var W3CWebSocket = require('websocket').w3cwebsocket;
this.client = new W3CWebSocket('wss://ws.bitstamp.net');
this.client.onerror = function() {
console.log('Connection Error');
};
this.client.onopen = function() {
console.log('WebSocket Client Connected');
var subscribeMsg = {
"event": "bts:subscribe",
"data": {
"channel": "live_trades_btcusd"
}
};
this.client.send(JSON.stringify(subscribeMsg));
};
this.client.onclose = function() {
console.log('echo-protocol Client Closed');
};
this.client.onmessage = function(e) {
if (typeof e.data === 'string') {
var bitstampPrice = JSON.parse(e.data).data.price;
console.log(bitstampPrice);
this.connection.sendUTF(bitstampPrice);
}
};
});
//this.connection.sendUTF(JSON.stringify({ type: "history", data: "data"} ));
}
}
module.exports = (httpserver) => { return new WebSocketCalss(httpserver) }
It maybe hairy, so this is what I am trying to do:
My NodeJS server will open a WebSocket connection to my client (browser)
In this WebSocket, I want to send a value that is received from another WebSocket (that is, my NodeJS will connect as a client)
Things seem to work fine individually, however, when I try to send the value (that I received as a client), to my own client (as I am the server), I get
Cannot read property 'send' of undefined
Basically, inside the callback, the this variable are not defined. It is as if this is a new object.
I am not familiar with ES6 so I believe I am doing something fundamentally wrong.
If anyone could shed some light in to this that'd be very much appreciated.

Answer 1

When you use this inside a function(), the context of the this is bound to the function and not the outside class.
this.client.onopen = () => {
console.log('WebSocket Client Connected');
var subscribeMsg = {
"event": "bts:subscribe",
"data": {
"channel": "live_trades_btcusd"
}
};
this.client.send(JSON.stringify(subscribeMsg));
};