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Angular 10 subscribe is failing to post with error code OK(and no other errors shown)

I am new to angular 10 and I am trying to make an http post to a PHP file as shown below
this.http.post(`${environment.server}/path/file.php`, {param1, param2})
.subscribe(
data => {
console.log(JSON.stringify(data));
},
error => {
console.log(error);
this.error = error;
});
The file is successfully called and returns the following JSON as displayed in the console response
{"Email":null,"school_year":2021,"academic_year":"2021"}
When I make the request I am immediately taken to the error state and all the console log is showing below only prints "OK"
console.log(error);
The two questions are the following
Why am getting to the error when the file is successfully returning JSON
Is there a way to get a more helpful error message than just OK

You will need to set the content type to application/json
You would be better off if you used a rest API rather than using php files. .NET Core or Node.JS would give you a better development experience.

It seems that your back-end PHP send the response with status code 400. It should be revised to 200 to get the data in response. When Status code is in Error range like 400, 401, 403 ... http Response will resolved in error or catch part.
In addition if you want just get data, it's better to use GET instead of POST.

error description from http error code - react.js/javascript

I have a Component in my react.js application, which display an error code.
Like this:
Now I'm displaying just a code, along with this what I want to to is - show the reason of this error too. Like this page contains a lot of information about error codes.
How can I do it ?
If I get any error, then I get the error code and use window.location="/bad_request/".concat(err_code);
In my ErrorPage component I've :
componentWillMount() {
this.state.errorCode = this.props.match.params.errorCode;
console.log(this.state.errorCode);
}
Rest is simple.

In common, HTTP response codes are being used for describing a general result of the response. For example, server should return one of 20x codes (200, 201, 202, ...) on some success operation or 40x (400, 401, 401, ...) on client error etc.
That said, code itself won't describe an actual request result in details so you have to do consider an error code only like general reference point.
Answering to you question, I'd suggest you need to take a following steps:
1. Review your server response structure to make it include an actual error message in response body.
2. Review your component structure to retrieve error message from response body to display it (or perform any other required actions)

Basically this error indicating that server didn't receiving complete req. in its time period So it is giving this error So you use increase server timeout as well as you can check with sending less data on server. For more info:
https://airbrake.io/blog/http-errors/408-request-timeout

I wrote this to my java-script file :
let map = new Map();
map.set(400,'Bad Request');
map.set(401,'Unauthorized');
...
When I get redirected to this page, I just get what was the description of the error.
Now I have entered all the data manually, I was just asking if there was any automated way to log these.

Flush and send response object periodically in Node.js

I am new to Node.js and i am trying to refresh the data periodically using the below code:
router.post('/getMessage',function(req,res){
setInterval(findMessage,5000);
function findMessage() {
Message.find(
{
$or: [
{sender: req.body.sender, receiver: req.body.receiver},
{sender: req.body.receiver, receiver: req.body.sender}
]
},
(err, data) => {
res.send({success: true, data: data});
}
);
}
});
But this gives an error: "Cannot set headers after they are sent". I understand that res.send calls res.end() implicitly and therefore this error is occuring. And have tried res.write() also. But i am returning an object and not a String or buffer, hence it also failed to work.
It would be great if someone could give an example of how to achieve this exactly.

response.send() method does two task
1. write content on the response and send.
2. End connection with res.end().
So, when you did response.send(), then it sends your message and closes the connection. For that reason, you getting the error "Cannot set headers after they are sent".
So, the conclusion is that you can't send multiple responses using response.send().
You can achieve this by the socket.io or you can make the request from frontend after an interval.

Reading the error value in Javascript

I am handling the error in a if block in the method where I receive the response from the server. I put the server down in order to test the service unavailable scenario
_onResponse: function (err, res) {
if (err){
}
on doing alert("error " + err);
I receive
Error: Request has been terminated
Possible causes: the network is offline, Origin is not allowed by Access-Control-Allow-Origin, the page is being unloaded, etc.
at Request.crossDomainError (http://localhost:9000/index.js:33875:14)
at XMLHttpRequest.xhr.onreadystatechange (http://localhost:9000/index.js:33945:20)
I want to read the value of Error:
I tried doing err.message but then I receive the entire body of the error.
I tried with err.name I just get the text 'Error'
How do I get the content Request has been terminated in a javascript variable?

From the response all I can say is this is not the error your server is sending. It is raised by the engine while doing XHR to a domain for which CORS is disabled. To catch this error, wrap the XHR code in index.js around line 33945 in a try{} catch(e){} block. Inside catch block you get hold of the error using the e variable.
Your block will handle error only when you get a response from the target server.

How to catch socket.io errors and prevent them from showing up in the console?

I'm running socket.io on node.js and the socket.io client on an Apache website. If I don't start the node.js server and load the client page, the error event is triggered with an empty error message, which results in the following console output:
GET http://example.com:1337/socket.io/1/?t=1359731838906 socket.io.js:1659
Socket.handshake socket.io.js:1659
Socket.connect socket.io.js:1699
Socket socket.io.js:1551
io.connect socket.io.js:94
(anonymous function) general.js:7
(anonymous function)
What can I do to stop this error being written to the console?

You can not "catch" these errors in the sense that they are not appearing in the console but you can still act upon them by listening for 'connect_error', 'connect_failed' and 'disconnect' of the socket and then either handling them directly or redirecting them to a custom function like handleErrors():
const socket = io.connect(url, { reconnection: false })
socket.on('update', data => console.log(data))
socket.on('connect_error', err => handleErrors(err))
socket.on('connect_failed', err => handleErrors(err))
socket.on('disconnect', err => handleErrors(err))

The only way to hide that error is by never calling io.connect in the first place – which of course would mean your app's socket functions wouldn't work even if the server is up.
It's important to understand that the error message you're seeing is neither something placed there by socket.io itself (via console.error()) nor is it an uncaught JS Exception.
The error message is placed in your console by the browser's XHR object itself. It's telling you that a XHR request has failed (since your server isn't running). The stack trace is telling you what code initiated the XHR request; it isn't a trace of an actual Exception.
Since socket.io must make a request to the server, there's no way it (or you) could prevent that error message from appearing in the console if the server isn't responding.

try
socket.on('connect_failed', function(){
console.log('Connection Failed');
});
Not tested this. Found it here Node.js socket.io-client connect_failed / connect_error event

If you're using Socket.io v4 and need to capture middleware errors, try
// client-side
socket.on("connect_error", (err) => {
console.log(err.message); // prints the message associated with the error
});
source https://socket.io/docs/v4/middlewares/#handling-middleware-error