Hello Im a bit confused about this error and what im doing wrong, here is my code

const { Connection, clusterApiUrl } = require('@solana/web3.js');

const connection = new Connection(clusterApiUrl('mainnet-beta'), 'confirmed');
//below is for getblock
GetBlockConfig: {
  commitment: 'finalized';
  rewards: false;
  transactionDetails: "full";

//below is for get transactions
GetVersionedBlockConfig: {
  commitment: 'finalized';
  maxSupportedTransactionVersion: 0;
  rewards: false;
  transactionDetails: "full";

async function fetchCurrentSlot() {
  const currentSlot = await connection.getSlot();
  console.log('Current slot:', currentSlot);
  return currentSlot;

async function fetchBlock() {
  try {
      const currentSlot = await fetchCurrentSlot();
      const block = await connection.getBlock(currentSlot, GetBlockConfig);
  } catch (error) {
      console.error("Error fetching block:", error);


and this is the error im getting

Current slot: 265806271
Error fetching block: ReferenceError: GetBlockConfig is not defined
    at fetchBlock (C:\Users\user\OneDrive\Desktop\Solana sniper\solana.js:30:60)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)

Im confused as to why its not defined, the formatting seems to be right comparing it to the docs so im not sure. I would appreciate some help on this.

Thanks and have a nice day!

1 Answer 1


This looks like a syntax error in JavaScript. Try defining the object separately as:

const GetBlockConfig = {
  commitment: 'finalized',
  maxSupportedTransactionVersion: 0,
  rewards: false,
  transactionDetails: "full",

You can see how this is being used in some of the tests, like at: https://github.com/solana-labs/solana-web3.js/blob/26dae190c2ec835fbdaa7b7d66ca33d6ba0727b8/packages/library-legacy/test/connection.test.ts#L6126

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