Ethers.js How to subscribe to pending transactions using ethers.Contract

If you want to subscribe to pending transactions you can use the ethers.Contract class to create a contract instance for the address you want to monitor and then listen for the pending event.

Here’s an example:

const { ethers } = require('ethers');

const provider = new ethers.providers.JsonRpcProvider('');

const abi = [
  'event Transfer(address indexed from, address indexed to, uint256 value)'

const contractAddress = '0x1234567890123456789012345678901234567890';

const contract = new ethers.Contract(contractAddress, abi, provider);

contract.on('pending', (txHash) => {
  console.log(`New pending transaction: ${txHash}`);

In this example, we’re using the JsonRpcProvider class from ethers.js to connect to the Ethereum network through Infura. We’re also specifying the ABI for a sample ERC20 token contract and the address of the contract we want to monitor.

Next, we’re creating a contract instance using the Contract class and passing in the contract address and ABI. We can then use the on method of the contract instance to subscribe to new pending transactions.

When a new pending transaction is detected, the callback function is called with the transaction hash as its argument.

Note that this method may not work for all contracts and events. You may need to modify the ABI and event names to match the contract you’re monitoring. Also, as with the previous method, you may still be rate limited by your Ethereum node or API provider.


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