Can't send a message to Node.js websocket server from React client

Question

I have following code as a server:

var http = require('http'),
    cors = require('cors'),
    connect = require('connect'),
    WebSocketServer = require('ws');

var DataController = function() {
    this.PORT = 8090;
    this.startWS();
    this.startServer();
}

DataController.prototype = {
    // code to start server...

    getMessage: function(_message) {
        var that = this,
        message = JSON.parse(_message),
        msgName = message.name;
        console.log('new message ' + msgName);
    switch(msgName){
        case 'start':
        // here is some code to perform actions
}

As you can see here I have getMessage function that fires some events and to invoke it I need to send a message start. That's easy enough, right? Surpisingly for me, it's not. That's how I try to perform this .send() method in my React component (my React app is running on different port of course):

import React, { Component } from 'react';

class App extends Component {

    componentDidMount() {
        const socket = new WebSocket('ws://localhost:8090');
        socket.onopen = function() {
            socket.send(JSON.stringify({message: "start"}));
        }
    }
    render() {
        return (
            <div className="container">App</div>
        )
    }
 }

 export default App;

What I try to accomplish here - I need to send just one word - start to actually start receieving data from server but I can't and do not understand why. See, there's a console.log() statement in my server code that logs a message start when it's sent. So it actually should log start but it logs undefined instead. What I tried so far: 1. Send just start 2. Define an object like this:

const data = {
    message: "start"
}

And then pass data to .send() function 3. Define just a variable like this: const data = "start"

And nothing above works!Everything returns undefined on server side. I'm just getting started with websockets and can't find a way to get it working. I refered mostly to Mozilla and it didn't work too. So what actually am I doing wrong in this case? Thanks in advance, I appreciate any help!

Answer 1

It appears to me that the object you are sending over in your .send() does not contain a name key, so when you then define msgName as message.name it evaluates to undefined as that key does not exist in the object.

You can change this easily by changing the object you send over so that the key "start" is tied to would be called name.