Develop Reference

A way to stop WebSocket errors to show up in browser's console

So the problem is when I try to initiate a new WebSocket to a remote host, sometimes the browser's console prints a red error message and complains about a refused connection, here is the message:
Error in connection establishment: net::ERR_CONNECTION_REFUSED
Having an error is fine since the remote host might be not responding sometimes, but the fact that I cannot handle this error message is very annoying.
Is there any way to either handle this error message or check whether the remote host accepts the WebSocket connection before initializing one in my JavaScript code??

Several possibilities come to mind:
Add a WebSocket.onerror error handler
myWebSocket.onerror = myEventHandler;
Wrap your "connect" in a try/catch block
try {
const connection = new WebSocket(myUrl);
...
}
catch(error) {
console.error(error);
}
Structure your code such that your I/O is event driven:
https://developer.mozilla.org/en-US/docs/Web/API/WebSocket#Examples
// Create WebSocket connection.
const socket = new WebSocket('ws://localhost:8080');
// Connection opened
socket.addEventListener('open', function (event) {
socket.send('Hello Server!');
});
// Listen for messages
socket.addEventListener('message', function (event) {
console.log('Message from server ', event.data);
});
// Handle errors
socket.addEventListener('error', function (event) {
console.log('WebSocket error observed:', event);
});
ADDENDUM:
The above methods allow you to completely handle a websockets exception.
Regardless of whether the exception is handled or not, the Chrome debugger will tell you if an exception has occurred. This is a Good Thing. It's called a "First-Chance Exception":
https://learn.microsoft.com/en-us/security-risk-detection/concepts/first-chance-exception
.. it is known a “first chance” exception – the debugger is given the
first chance of inspecting the exception prior to the application
handling it (or not).
In Microsoft's Visual Studio debugger, there's a little checkbox you can use to "gag" first chance exceptions. I'm not aware of any similar "checkbox" in Chrome debugger.
POSSIBLE SUGGESTIONS:
Chrome debugger has a "filter". EXAMPLE FILTER REGEX: ^((?!ERR_CONNECTION_REFUSED).)*$
This link suggests you might be able to use the filter to "Hide Network Messages" (I haven't tried it myself). See also this link.

Firebase Auth sendEmailVerification() I'm getting an Error, but only with Safari browser

When a user signs up, I am requiring them to verify their email address.
It works fine in Firefox and Chrome, but not in Safari, where I get the following message:
Error: A network error (such as timeout, interrupted connection or unreachable host) has occurred.
And no confirmation email is sent.
I’m sourcing this version:
firebasejs/6.4.0/firebase-auth.js
I've searched for similar problems. There were lots of Firebase Authentication errors, but I didn't find this one.
Using the Safari JavaScript debugger, filtering for all exceptions I receive the errors below.
And interestingly, after stepping through with the debugger on, setting Breakpoints at "All Exceptions" an email is sent. But not when running in real-time.
Hopefully that is a clue.
I send the email verification with this code.
if (current_user && !current_user.emailVerified) {
current_user.sendEmailVerification().then(function() {
const user_message = '<message to user>';
window.location = '/message?message=' + user_message;
}).catch((error) => {
console.log(error);
} );
}
The errors:
line 515 rpchandler.js
try {
response = JSON.parse(this.getResponseText()) || null;
It looks like the response is null.
line 183 promise.js Exception with thrown value: zi
try {
// Promise was rejected. Step up one call frame to see why.
if (reason instanceof Error) {
throw reason;
This happens a few times.
line 2190 authuser.js
// Cache the invalidation error.
self.userInvalidatedError_ = /** #type {!fireauth.AuthError} */ (error);
line 740 firebase-app.js
Exception with thrown value: TypeError: Argument to String.prototype.startsWith cannot be a RegExp
Any ideas?

I ended up rolling my own email verification workflow.
I'd be interested in reverting back to the Firebase Auth JavaScript email verification workflow, if there is a solution. But for now, I just have to move forward.

Why does `websocket.close()` before connection establishes triggers `onerror`?

Calling websocket.close() before connection is established triggers onerror. I wasn't able to figure out what the error is, nor where it came from.
const connection = new WebSocket("wss://echo.websocket.org");
connection.onopen = () => {
console.log('open');
}
connection.onerror = (error) => {
throw error; // this is thrown
}
connection.close();
Tested in chrome dev console. onerror is being triggered when close is called.
If I wait until the connection is established before calling close, no error is thrown. I wonder what the error is
Edit:
included the error output:

I took my own advice and checked it out - and it gave me this:
Not sure if that answers your question if I say that it's more strange not to expect an error when you're not waiting for a connection before closing a socket.
Just handle it with a try-catch or put your connection.close() inside your onopen handler?

NodeJS Sockets Sometimes Working

So, I have a node server, running expressjs io (uses socket.io), and I'm building a grid map that tracks coordinates in a database.
Only, I've run into a peculiar issue in that my sockets only listen sometimes.
At first there was no error message, and only by chance I let the page run and I got this error.
Uncaught TypeError: Cannot call method '0' of undefined UkPS99A_w96Ae0K570Nt?t=1395276358213&i=0:1
When I click on the file UkPS99A_w96Ae0K570Nt?t=1395276358213&i=0:1 I get this code:
io.j[0]("8::");
If I refresh the page, every few times it will suddenly work find for about 10 tile clicks, and then it stops working. My database is updating properly until the sockets basically die out.
Here is where I send the coordinates in my map:
io.emit("move", {x:this.x,y:this.y});
Server listening:
app.io.route('move', function(req) {
con.getConnection(function(err){
if (err) console.log("Get Connection Error.. "+err);
//removed query because redundant
req.io.emit("talk", {x:req.data.x,y:req.data.y});
});
});
and my socket script:
io.on("talk",function(data) {
console.log(data.x,data.y);
});
My script includes are at the bottom of the page in this order:
<script src="socket.io/socket.io.js"></script>
<script>io = io.connect();</script> <!-- open the socket so the other scripts can use it -->
<script src="../js/sock.js"></script>
<script src="../js/map.js"></script>
Is there something I'm doing wrong to that the socket seems to lose connection and throw some sort of error?
Update: I left the server running longer and a couple more error messages popped up in my console:
Uncaught TypeError: Cannot call method 'close' of null socket.io.js:1967
Uncaught TypeError: Cannot call method 'close' of null socket.io.js:1967
Uncaught TypeError: Cannot call method 'onClose' of null
More update: altered the connection line and added the proper CORS to my server.js
io = io.connect('http://sourceundead.com', {resource : 'socket.io'});
Still the same issue.

You seem to have a connection attrition as you never release them to the pool.
Assuming con is the (bad) name of your pool, instead of
app.io.route('move', function(req) {
con.getConnection(function(err){
if (err) console.log("Get Connection Error.. "+err);
//removed query because redundant
req.io.emit("talk", {x:req.data.x,y:req.data.y});
});
});
you should have something like
app.io.route('move', function(req) {
con.getConnection(function(err, connection){
if (err) console.log("Get Connection Error.. "+err);
//removed query because redundant
req.io.emit("talk", {x:req.data.x,y:req.data.y});
connection.release();
});
});
Be careful that using connections must be done with care to ensure they're always released, and it's a little tedious to do especially when handling errors as soon as you have a few queries to do when doing a task.
At some point you might want to use promises to make that easier. Here's a blog post about using bound promises to ease database querying in node.js.

Why am i getting this error running 'net' module node.js

I am using .net modular and opening tcp port on 6112.
var net = require('net');
var server = net.createServer(function (socket) { //'connection' listener
});
server.listen(6112, function () { //'listening' listener
console.log('server started');
});
On the same machine i start a java socket in main.
public static void main(String[] args) {
// TODO Auto-generated method stub
try {
System.out.println("Connecting...");
Socket socket = new Socket("localhost", 6112);
System.out.println("Connected");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
I get this exception,
C:\Users\Mustafa\WebstormProjects\Node.Js>node hello.js
server started
events.js:72
throw er; // Unhandled 'error' event
^
Error: read ECONNRESET
at errnoException (net.js:884:11)
at TCP.onread (net.js:539:19)
Is this like a bug or something, cause if once i get through this bug, I will be good thanks.
I haven't used the debugger cause as Ryan said it him self a year ago that it is still shitt.

You need to listen for errors on the socket. Node has the default behavior that when something does .emit('error'), if there are no error handlers attached, it will throw the error instead, thus crashing the application.
var server = net.createServer(function (socket) {
socket.on('error', function(err){
// Handle the connection error.
});
});

You are creating a socket and connecting from it, but not closing it. So when the program finishes, to node.js it looks like connection is reset (closed abruptly). Call socket.close(); before program finishes.
You can structure your code in this way :
try {
tryStatements //your code that is causing exceptions
}
catch(exception){
catchStatements //handle caught exceptions
}
finally {
finallyStatements //execute it anyways
}
Or if you like to catch uncaught exceptions from runtime, use this (main process won't exit on exceptions)
process.on('uncaughtException', function(err) {
console.log('Caught exception: ' + err);
console.log(err.stack);
});
The problem is in java code which is causing node.js to exit on exception. So be sure to add socket.close();. Above is just error handling on node.js part.