transactionChecker-2.js

const Web3 = require('web3');

class TransactionChecker {
    web3;
    web3ws;
    account;
    subscription;

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

    subscribe(topic) {
        this.subscription = this.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(process.env.INFURA_ID, '0xe1Dd30fecAb8a63105F2C035B084BfC6Ca5B1493');
txChecker.subscribe('pendingTransactions');
txChecker.watchTransactions();

How can be watched from a single block predefined block to latest (predefined when i deployed my contract) for our offchain users so when i try to do with setInterval with loop my server get stuck after a time.

How can be watched from a single block predefined block to latest (predefined when i deployed my contract) for our offchain users so when i try to do with setInterval with loop my server get stuck after a time.

Did you succeed? What you can do is when a transaction is initiated you need to call this function from outside ex: ui and when the transaction is confirmed we can have delay so that some blocks get added to the chain and transaction is verified. You can clear the interval after that for this function. Let me know if you did any other solution for this.