Out of boredom I currently try to create a simple chat-app on my localhost.

To start this all out, I began with a plain react app based on create-react-app.
In there I have the following code to start a WebSocket communication.

  // on localhost:3000

  componentDidMount = () => {

    this.ws = new WebSocket('ws://127.0.0.1:5000');



    this.ws.on('open', () => {

      this.ws.send(this.props.userName + ' has joined the Chat.');

    });



    this.ws.on('message', (message) => {

      const messages = this.state.messages;

      this.state.messages.push(message)

      this.setState({ messages: messages })

    });



    console.log('Component mounted.')

  }

Whenever I try this at runtime with npm start to communicate with the counterpart WebSocket server that looks like the following and started on the same machine with node server.js

// File: server.js

const WebSocket = require('ws');

const wss = new WebSocket.Server({ port: 5000 });



wss.on('connection', function connection(ws) {

    ws.on('message', function incoming(message) {

        console.log('received: %s', message);

    });



    ws.send('something');

});

I get the following issue:

Access to fetch at 'http://127.0.0.1:5000/' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

To solve this I've already tried:

1. Access-Control-Allow-Origin extension for chrome no effect.


2. To set the following proxy in package.json proxy: http://localhost:5000 - also no effect.


3. As a kind of last resort I tried to launch google-chrome with google chrome --disable-web-security --user-data-dir=/tmp - in this case i get the following: GET http://127.0.0.1:5000/ net::ERR_ABORTED 426 (Upgrade Required) and from here on I'm lost.

Can anyone help me out on this issue? Would this be possible in general or is there a flaw in my thinking?

I'm not a webdeveloper of anykind and usually do C++... Sorry if that all seems stupid.

Regards
Jack