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How to set Heroku Port for NodeJS Express App?

so I'm trying to host my website on Heroku and set up everything to get my app up and running.
Whenever I try to submit the form I get undefined errors.
Undefined Errors Console Errors
I've set it up to use the port like shown in the documenation:
app.listen(process.env.PORT || 8081, function () {
console.log('Example app listening on port 8081!');
});
When starting the app locally with heroku local web I get Typerror: Failed to Fetch and the undefined results but when I go into my .env file and add a port=8081 it works perfectly fine.
Good result
When I open it with heroku open I still have that undefined problem.
I don't really have to set a PORT in .env right? Or do I?
I read that that standard port is 80 but that didn't work either.
Can someone please help me?
Thank you!
Heres the link to the public site: https://shrouded-everglades-61993.herokuapp.com/
Here the link to my Github rep: https://github.com/stefanfeldner/capstone-travel-app

So the reason that they're undefined is that they are being set by these lines in main.js:
uiData.imageURL = data[1].imageUrl;
...
uiData.iconCode = data[0].iconCode;
Where data is the object you're retrieving from your /getData endpoint. The problem is that what /getData actually returns is [{}, {}] so of course these values are both undefined, leading to that visual broken-ness.
Now, why does /getData return these empty objects? I can't check your server logs, but there are two obvious possibilities based on the way server.js is written.
The first is that there's an error somewhere and you're simply not making it all the way to the end of your try-catch in callApi, so neither weatherData nor pixabayData are being updated.
Second, it's also possible that these calls are successful but that the desired data is not in the results, i.e. that neither of these if statements are true:
if('city_name' in data) {`
...
if('hits' in data) {
Again, in this case, neither weatherData nor pixabayData are being updated.
The way that your handler for /sendFormData is written, it doesn't check that callApi actually got any useful data, just that it has finished execution. So your code flow continues on its merry way despite the data objects still being empty.
However, there's a bigger, unrelated design flaw here: What happens if more than one person uses your website? Your client-side code calls /sendFormData, which hopefully correctly populates the global variables weatherData and pixabayData, and then separately calls /getData to try and retrieve this data.
The thing is, though, between the time your client-side calls /sendFormData and /getData, anyone else using your website could separately call /sendFormData and change the data contained in the global variables from the result of your search to the result of their search. So you'd get their search results back instead of yours, since their results overwrote your results on the server. You need to handle getting the API results and sending them back to the requester in a single transaction.
(Re: all the local Heroku Config, that's hard to answer without messing around with your local computer, sorry.)

Angular and Server Sent Events: close method call does not close the data stream

Tech stack: Angular 7, Spring webflux (with spring boot), Chrome browser
I cannot share the actual code due to policy restrictions. Appreciate your understanding.
I have followed this example: https://medium.com/#chrisbautistaaa/server-sent-events-in-angular-node-908830cc29aa
I have a boolean variable makeCall acting as a condition switch for my if else
When user clicks a button on screen toggleSseCall method containing the below logic is called in Angular component
Body of toggleSseCall method:
makeCall: boolean = true;
toggleSseCall() {
let eventSource = new EventSource(url);
if(makeCall) {
Call service method: getServerSentEvents(eventSource) //similar to the example in link one difference being i'm passing the Instantiated eventSource reference
Subscribe to the observable returned by the above call like in the example and console log the data
} else { //When user clicks the button again, call goes here as makeCall is false
//Call flow comes here as expected, I verified that with console logging
eventSource.close(); //I verified to make sure the close method is not uppercase or anything like that
}
makeCall = !makeCall //toggle boolean flag
}
Server side:
Just RESTFul Get Api call that returns Flux and the Flux just returns hello string every x seconds
The call is happening and the "hello" text streams from back-end to front-end as expected. But, the data stream doesn’t stop on call to close method. I want the data stream to close when user clicks the button again. Would appreciate any suggestions on this.

A bit late, but I just came across this issue myself. For me, this only happens when developing locally via ng serve, using the Webpack dev server to proxy requests to my backend app.
The proxy is implemented using the NPM package http-proxy-middleware. There's
an unresolved issue suggesting this is a bug.
When the browser connects directly to the backend API, this issue doesn't happen for me.

Ionic-Angularjs | Write logging to file or variable

I'm working on a new project using Ionic (AngularJs-based) and everything is working as it should be.
I'm currently outputting every 'Function call' (every step) to the console (via a Debug-Function) for debugging purposes so that I can quickly see if every function gets called correctly.
Log Function (minimised/simplified code):
.factory('DebugMode', ['$log', function($log) {
var DebugMode = {};
this.active = true;
this.console = function(LogLine, LogStyle)}
if(DebugMode.active){
$log.log(LogLine);
}
};
return DebugMode;
My question:
Is there a way or a method that I can also write that output (not specific the console output, but the logs I write to it) to a file or variable?
My purpose: Able to request the log when I'm running the app stand-alone and don't have access to a browser or some sort. So that I can easily see if everything is still running correctly or if a client is experiencing some issues, I can ask them to send the Log via mail or some sort.
For ex. (in the app): Open the menu, go to settings, show log, see where the app returned an error and/or press a button to send that log to me.
Would the best way be to write everything to a 'log-output.date().txt' sort of thing or store everything in a session variable that gets cleared on exit?
Thanks in advance!
-Bert

After some research, I think FileLogger would be the best solution and does exactly what I had in mind (more or less).

Auto detect if DB table changes

I have a small application where a users can drag and drop a task in an HTML table.
When user drops the task, I call a javascript function called update_task:
function update_task(user_id, task_id, status_id, text, uiDraggable, el) {
$.get('task_update.php?user_id='+user_id+'&task_id='+task_id+'&status_id='+status_id+'', function(data) {
try {
jsonResult = JSON.parse(data);
} catch (e) {
alert(data);
return;
};
In task_update.php I GET my values; user_id, task_id & status_id and execute a PDO UPDATE query, to update my DB. If the query executes correctly, I
echo json_encode ( array (
'success' => true
) );
And then I append the task to the correct table cell
if(typeof jsonResult.success != 'undefined') {
$(uiDraggable).detach().css({top: 0,left: 0}).appendTo(el);
}
This has all worked fine. But, I'm starting to realize, that it's a problem when 2 or more people are making changes at the same time. If I'm testing with 2 browsers, and has the site opened on both for example: Then, if I move a task on browser1, I would have to manually refresh the page at browser2 to see the changes.
So my question is; How can I make my application auto-detech if a change to the DB-table has been made? And how can I update the HTML table, without refreshing the page.
I have looked at some timed intervals for updating pages, but that wouldn't work for me, since I really don't want to force the browser to refresh. A user can for example also create a new task in a lightbox iframe, so it would be incredibly annoying for them, if their browser refreshed while they were trying to create a new task.
So yeah, what would be the best practice for me to use?

Use Redis and its publish/subscribe feature to implement a message bus between your PHP app and a lightweight websocket server (Node.js is a good choice for this).
When your PHP modifies the data, it also emits an event in Redis that some data has changed.
When a websocket client connects to the Node.js server, it tells the server what data it would like to monitor, then, as soon as a Redis event was received and the event's data matches the client's monitored data, notify the client over the websocket, which then would refresh the page.
Take a look at this question with answers explaining all of this in detail, includes sample code that you can reuse.

I would use ajax to check the server at a reasonable interval. What's reasonable depends on your project - it should be often enough that it changes on one end don't mess up what another user is doing.
If you're worried about this being resource intensive you could use APC to save last modified times for everything that's active - that way you don't have to hit the database when you're just checking if anything has changed.
When things have changed then you should use ajax for that as well, and add the changes directly in the page with javascript/jquery.

If you really need to check a db changes - write a database triggers.
But if nobody, except your code, change it - you can to implement some observation in your code.
Make Observation(EventListener) pattern imlementation, or use one of existed.
Trigger events when anything meaningful happened.
Subscribe to this events

Notifications in javascript without user input

I've been trying to figure out a way to use notifications on a background process and couldnt find anything online about it. So, I figured out one way around it and wanted to share (Not sure if this is the best way to go about doing this but here goes:)
Problem: I want to notify the user of new info when the page is running but in the background (blurred). I could use alert('new info!'); to get the taskbar icon to flash, but then you have to manually dismiss it (tried it and it's hella annoying). I really liked the notifications, but they only work if the user performs an action, so not helpful...

I hope I won't be telling something stupid, but from where I see it (and remember from school) that's basically how http works : a request is sent to the server, which issues a response eventually after executing some server-side code.
Basically you're asking for a "PUSH" functionality from server to client, and in that case you can't make use of HTTP.
Some tricks exist to work around this limitation, but basically they're all issuing requests at a certain frequency (Dave's answer does exactly that). If your site doesn't change that much, that means a lot of requests are issued for no reason (nothing has changed), consuming bandwith for nothing.
From what I know, the answer to this is called Websockets, which are supported by recent browsers only. I never had the chance to use it though so I couldn't tell much more about it. This allows full duplex communication, thus allowing server to "push" data to the client. I guess that's what SO uses for "new message" notifications (top left of the screen - you see immediately when you receive a new message)

My solution: I made a chrome extension that runs in the background and triggers the notifications. It's a little limited in scope as you need to have chrome to do it, but it does what i need it to, and for the purposes of the problem i'm working on, i can just make my user group use chrome ;D
The specifics: The extension only has two components, the manifest and a script. Currently, i setup the manifest so that it only works on my site using the match identifier... and i set the permissions to include notifications.
The JS script has a window.setinterval that looks for an element in the page with the id NOTIFIER. If it's empty, it does nothing, otherwise it creates a notification based on the content and then clears the content to prevent showing the same notification multiple times... (I tried using .onchange for that element, but couldn't get the event to trigger... I'd prefer to do this on an event rather then setInterval)
Notify.js
function onExtLoad() {
var timer = setInterval(refresh,1000);
}
document.addEventListener('DOMContentLoaded', onExtLoad());
function refresh() {
if (document.getElementById('NOTIFIER').innerHTML == "") {
//do nothing?
} else {
var notification = webkitNotifications.createNotification("",
"You got a new message",
document.getElementById('NOTIFIER').innerHTML);
notification.show();
document.getElementById('NOTIFIER').innerHTML = "";
}
}
Then, all i need to do is have the JS on the page control when it adds info the the NOTIFIER and voila! notifications!
Hope this helps someone else.
#ExpertSystem: I messed around with the MutationObserver but I can only get it to trigger once. Here's a JSFiddle: http://jsfiddle.net/BTX8x/1/
Am I missing something? Is there a way to reset it?
EDIT: Figured it out, i needed subtree:true