Question

If I run a server with the port 80, and I try to use XMLHttpRequest I am getting this error: Error: listen EADDRINUSE

Why is it problem for NodeJS, if I want to do a request, while I run a server on the port 80? For the webbrowsers it is not a problem: I can surf on the internet, while the server is running.

The server is:

  net.createServer(function (socket) {
    socket.name = socket.remoteAddress + ":" + socket.remotePort;
    console.log('connection request from: ' + socket.remoteAddress);
    socket.destroy();
  }).listen(options.port);

And the request:

var xhr = new XMLHttpRequest();

xhr.onreadystatechange = function() {
    sys.puts("State: " + this.readyState);

    if (this.readyState == 4) {
        sys.puts("Complete.\nBody length: " + this.responseText.length);
        sys.puts("Body:\n" + this.responseText);
    }
};

xhr.open("GET", "http://mywebsite.com");
xhr.send();

Answer 1

EADDRINUSE means that the port number which listen() tries to bind the server to is already in use.

So, in your case, there must be running a server on port 80 already.

If you have another webserver running on this port you have to put node.js behind that server and proxy it through it.

You should check for the listening event like this, to see if the server is really listening:

var http=require('http');

var server=http.createServer(function(req,res){
    res.end('test');
});

server.on('listening',function(){
    console.log('ok, server is running');
});

server.listen(80);