Question

147

Socket.io No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost' is therefore not allowed access

rated 0 times [ 154] [ 7] / answers: 1 / hits: 22970 / 10 Years ago, fri, january 30, 2015, 12:00:00

I'm trying to learn nodejs with socket.io and at the moment I'm using this tutorial by GianlucaGuarini. When entering my client.html file I get the following error. I know what it means and that it´s there for preventing Cross browser scripts but I don´t know how to allow my nodejs script to access the client.html file.

XMLHttpRequest cannot load http://localhost:8000/socket.io/?EIO=3&transport=polling&t=1422653081432-10. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost' is therefore not allowed access.

Here is a part of my code with socket.

  var app = require('http').createServer(handler),

  io = require('socket.io').listen(app),

  fs = require('fs'),

  mysql = require('mysql'),

  connectionsArray = [],

  connection = mysql.createConnection({

    host: 'localhost',

    user: 'root',

    password: '',

    database: 'database',

    port: 3306

  }),

  POLLING_INTERVAL = 3000,

  pollingTimer;



// If there is an error connecting to the database

connection.connect(function(err) {

  // connected! (unless `err` is set)

  console.log(err);

});



// creating the server ( localhost:8000 )

app.listen(8000);



// on server started we can load our client.html page

function handler(req, res) {



  res.writeHead(200, {

      /// ...

      'Access-Control-Allow-Origin' : '*'

  });



  fs.readFile(__dirname + '/client.html', function(err, data) {

    if (err) {

      console.log(err);

      res.writeHead(500);

      return res.end('Error loading client.html');

    }

    res.writeHead(200);

    res.end(data);

  });

}

Does anyone know how I can solve my problem?

Kind regard / H

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shane

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4 Years ago

answered 10 Years ago kennedysaraiw · Accepted Answer

First of all - stop use writeHead everywhere. Because it rewrite completely response headers.

If tour write like this:

res.writeHead(200,{coolHeader:YesIAm});

res.writeHead(500);

then node.js will sent response just with status 500 and without header coolHeader;

If you wanna change Status Code, then use

res.statusCode = ###;

If you wanna add new header use

res.setHeader(key, value);

And if you wanna rewrite all headers then use writeHeader(...)

Second. Add this code

res.statusCode = 200;

//...

res.setHeader(Access-Control-Allow-Origin, *);

res.setHeader(Access-Control-Allow-Headers, Origin, X-Requested-With, Content-Type, Accept);

instead of your

 res.writeHead(200, {

      /// ...

      'Access-Control-Allow-Origin' : '*'

  });

and replace all writeHead(###) with res.statusCode = ###;