Why can't I establish a socket connection with Infura? Project ID is correct, I triple checked

Question

I want to subscribe and listen to events that involve funds moving to my wallet, however I for some reason am not able to establish a socket connection to an Infura node.

First I npm init and npm web3.

The code:

const Web3 = require('web3');

class TransactionChecker {
    web3;
    web3ws;
    account;
    subscription;

    constructor(projectId, account) {
        web3ws = new Web3.providers.WebsocketProvider('wss://kovan.infura.io/ws/v3/' + projectId);
        web3 = new Web3.providers.HttpProvider('https://kovan.infura.io/v3/' + projectId);
        account = account.toLowerCase();
    }

    subscribe(topic) {
        this.subscription = web3ws.eth.subscribe(topic, (err, res) => {
            if (err) console.error(err);
        });
    }

    watchTransactions() {
        console.log('Watching all pending transactions...');
        this.subscription.on('data', (txHash) => {
            setTimeout(async () => {
                try {
                    let tx = await this.web3.eth.getTransaction(txHash);
                    if (tx != null) {
                        if (this.account == tx.to.toLowerCase()) {
                            console.log({address: tx.from, value: this.web3.utils.fromWei(tx.value, 'ether'), timestamp: new Date()});
                        }
                    }
                } catch (err) {
                    console.error(err);
                }
            }, 60000)
        });
    }
}

let txChecker = new TransactionChecker('projectId', 'address');
txChecker.subscribe('pendingTransactions');
txChecker.watchTransactions();

Gives me the following err: 'failed to create stateful backend, closing connection: websocket: bad handshake'

URLs are all good, why the error?

Answer 1

It is creating a provider instance, it also needs creating a Web3 with the provider. It can combine the two steps like this

web3 = new Web3('wss://kovan.infura.io/ws/v3/' + projectId)

It is doing something like

web3provider = new Web3.providers.WebsocketProvider('wss://kovan.infura.io/ws/v3/' + projectId)
web3 = new Web3(web3provider)