2

I'm new to Node.js .

I'm trying to do a POST request to my Node.js server running locally on port 8080.

But it doesn't work.

FireFox block my POST request because it is cross-origin

Reason: CORS request not HTTP

Here is my code:

HTML

<html>
<head>
    <title>Progetto Start</title>
    <script src="..\Controller\Start.js"></script>
</head>
<body>
    <input type="button" id="btPostJSON" value="invia JSON" onclick="SendJSON()"/>
</body>
</html>

Start.js:

function SendJSON() {
xhr = new XMLHttpRequest();
var url = "127.0.0.1:8080";
xhr.open("POST", url, true);
xhr.setRequestHeader("Content-type", "application/json");
xhr.onreadystatechange = function () { 
    if (xhr.readyState == 4 && xhr.status == 200) {
        var json = JSON.parse(xhr.responseText);
        console.log(json.email + ", " + json.name)
    }
}
var data = JSON.stringify({"email":"[email protected]","name":"LaraCroft"});
xhr.send(data);
}

Node js server:

var http = require('http');

http.createServer(function (req, res) {
res.writeHead(200, {"Content-Type": "text/html"});
res.write(req.url);
res.end();
console.log(req.url);
}).listen(8080);

I'm printing url to console and as a response only to see if it works There is someone that has already solved mine problem ?

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2
  • You need to have express js or similar library for http requests. Commented Oct 11, 2018 at 15:31
  • Basically, you are trying to make http request but you dont have anything that corresponds to that request in your node js. Commented Oct 11, 2018 at 15:34

2 Answers 2

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2

Just a quick note, CORS is required whenever the domain of the server/api does not match the domain of the calling client. If your port number on the client side does not match the port number on the server/api, the domains do not match and CORS is required

Shamelessly pulled from here: [https://bigcodenerd.org/enable-cors-node-js-without-express/][1]

Inside your createServer callback, put this:

   const headers = {
    'Access-Control-Allow-Origin': '*',
    'Access-Control-Allow-Methods': 'OPTIONS, POST, GET',
    'Access-Control-Max-Age': 2592000, // 30 days
    /** add other headers as per requirement */
  };

  if (req.method === 'OPTIONS') {
    res.writeHead(204, headers);
    res.end();
    return;
  }

  if (['GET', 'POST'].indexOf(req.method) > -1) {
    res.writeHead(200, headers);
    res.end('Hello World'); //Replace this with your response logic
    return;

  }

The if (req.method == "OPTIONS") block is your 'pre-flight' request. This is basically just used to check cors permissions for a resource.

There's also other packages that will do something similar for you. Replace the "*" with your specific client-side hostname ("something.com") for better security. Using the wildcard (*) is a security risk, so before putting something in production, you'll want to change that to whatever domain or ip address you want to let access your api.

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3 Comments

It tell me that app isn't defined
It is express js. You need to install it into your project with npm
I modified it for pure node.
0

You are missing the protocol from your URL. Add http:// to it and it should work.

var url = "http://127.0.0.1:8080";

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5 Comments

What is the address in the address bar? It should also start with http://127.0.0.1:8080 so that CORS is not needed (would be same-origin)
Are you sure that your JavaScript is not cached and that the version with "http://" URL is loaded?
If the page's origin is http://127.0.0.1:8080 and your AJAX request's origin is http://127.0.0.1:8080, then they are the same origin and not cross-origin, and CORS is not needed. Try it in another browser and see if you get a more helpful error message.
Maybe the error is caused by the fact that my html and js files are on a local path like file\\\c:/Desktop/prj ... ?
Yes. That is most likely the case. Use node.js to serve up your files so that they are from the server listening at 127.0.0.1:8080 and not your file system. Something like express would be convenient for that.