Ethereum: How to check if transaction is in mempool using Infura apis

Checking if a Transaction is in the Mempool using the Infura API

As a developer, it is essential to verify whether a pending transaction has been included in the Ethereum network mempool. In this article, we will explore two approaches: using Infura’s eth_getTransactionByHash API and implementing a JavaScript-based solution with Web3.js.

Approach 1: Using the eth_getTransactionByHash API

The eth_getTransactionByHash API allows you to retrieve a transaction by its hash. However, it is worth noting that this endpoint only returns transaction details if it exists in the mempool or is valid for inclusion in the mempool.

Here are the steps:

• Construct the Ethereum address of the miner who created the transaction.

• Send a request to eth_getTransactionByHash with the constructed address and the target hash of the transaction you are interested in (0x...). Replace “targetHash” with the actual hash you want to check.

const web3 = require('web3');
const infuraUrl = '
const provider = new web3.providers.HttpProvider(infuraUrl);
// Construct the Ethereum address of the miner who created the transaction
const minerAddress = '0x...';
// Construct the target hash of the transaction you are interested in
const targetHash = '0x...';
web3.eth.getTransactionByHash(provider, { from: minerAddress }, {
data: 0x ${targetHash},
})
.then((transaction) => {
console.log(transaction);
if (transaction.isInMempool()) {
console.log('Transaction is in mempool');
} else {
console.log('Transaction is not in mempool');
}
})
.catch((error) => {
console.error(error);
});

Approach 2: Using JS Web3.js and Infura API

For a simpler approach, you can use the eth.getTransaction method from Web3.js. This method has an optional hash parameter.

Procedure:

const web3 = require('web3');
const infuraUrl = '
const provider = new web3.providers.HttpProvider(infuraUrl);
// Construct the Ethereum address of the miner who created the transaction
const minerAddress = '0x...';
// Construct the target hash of the transaction you are interested in
const targetHash = '0x...';
web3.eth.getTransaction({
from: minerAddress,
gasprice: web3.utils.toWei('20', 'gwei'),
})
.then((transaction) => {
console.log(transaction);
if (transaction.isInMempool()) {
console.log('Transaction is in mempool');
} else {
console.log('Transaction is not in mempool');
}
})
.catch((error) => {
console.error(error);
});

Conclusion

Both approaches allow you to check whether a pending transaction has been included in the Ethereum network mempool. However, using eth_getTransactionByHash provides more information about the transaction and its inclusion status. The Web3.js JS method is a more straightforward solution.

In both cases, make sure your Infura API instance is properly configured with your project ID.

Note: This implementation assumes you have already set up an Ethereum node or connected to a cloud provider like Infura. If not, follow the setup instructions provided for each platform.

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