checkTxFinality.ts

/*
  Simple code snippet to check if an Ethereum Tx Hash has been finalized. 
  It will fetch the block number of the tx and compare it with the latest
  finalized block.
*/
import { ApiPromise, WsProvider } from '@polkadot/api';
import yargs from 'yargs';

const args = yargs.options({
  'tx-hash': { type: 'string', demandOption: true, alias: 'tx' },
  network: { type: 'string', demandOption: true, alias: 'n' },
}).argv;

// Create Provider
let wsProvider;
if (args['network'] === 'moonbeam') {
  wsProvider = new WsProvider('wss://wss.api.moonbeam.network');
} else if (args['network'] === 'moonriver') {
  wsProvider = new WsProvider('wss://wss.api.moonriver.moonbeam.network');
} else if (args['network'] === 'moonbase') {
  wsProvider = new WsProvider('wss://wss.api.moonbase.moonbeam.network');
} else {
  console.error('Network not supported');
  process.exit();
}

const main = async () => {
  // Create the provider using Moonbeam types
  const api = await ApiPromise.create({
    provider: wsProvider,
  });
  await api.isReady;

  // Get the latest finalized block of the Substrate chain
  const finalizedHeadHash = (await api.rpc.chain.getFinalizedHead()).toJSON();

  // Get finalized block header to retrieve number
  const finalizedBlockHeader = (await api.rpc.chain.getHeader(finalizedHeadHash)).toJSON();

  // Get the transaction receipt of the given tx hash
  const txReceipt = (await api.rpc.eth.getTransactionReceipt(args['tx-hash'])).toJSON();

  // We can not verify if the tx is in block because api.rpc.eth.getBlockByNumber
  // does not return the list of tx hash

  // If block number of receipt is not null, compare it against finalized head
  if (txReceipt) {
    console.log(`Current finalized block number is ${finalizedBlockHeader.number}`);
    console.log(
      `Your transaction in block ${txReceipt.blockNumber} is finalized? ${
        finalizedBlockHeader.number >= txReceipt.blockNumber
      }`
    );
  } else {
    console.log('Your transaction has not been included in the canonical chain');
  }

  await api.disconnect();
};

main();