How to Get the Number of Transactions in a Block

This guide assumes you’ve gone through the getting started steps and have an Alchemy account!

Each Block in a Blockchain is assigned a block number. It is the unique sequential number for each Block. Follow the steps below to return all transactions in the current finalized Block on Ethereum:

1. From your command line, create a new project directory and cd into it:

$
mkdir get-num-block-txns
>
cd get-num-block-txns

2. Install HTTP client library

You can use any HTTP library of your choosing. In this guide, we will make use of the Axios library for HTTP requests.

$
npm install axios

3. Create a file named index.js and add the following contents:

1
const options = {
2
  method: "POST",
3
  url: "https://eth-mainnet.g.alchemy.com/v2/{your-api-key}",
4
  headers: { accept: "application/json", "content-type": "application/json" },
5
  data: {
6
    id: 1,
7
    jsonrpc: "2.0",
8
    method: "eth_getBlockTransactionCountByNumber",
9
    params: "finalized",
10
  },
11
};
12
13
axios
14
  .request(options)
15
  .then(function (response) {
16
       console.log(response.data);
17
  })
18
  .catch(function (error) {
19
    console.error(error);
20
  });

This is an axios call, where a POST request is made to the Alchemy API and the data sent contains the particular endpoint called

$
method: "eth_getBlockTransactionCountByNumber",

And the param which specifies, returning information on the most recent finalized Block:

$
params: "finalized",

4. Run it using node

$
node index.js

You will see the following response logged to the console:

1
{ jsonrpc: '2.0', id: 1, result: '0xb3' }

This response is in HEX. To view it in decimal, you can add a simple convert function to the code:

5. Converting HEX to Decimal:

1
function hexToDec(hex) {
2
  return parseInt(hex, 16);
3
}

Convert the result response from Hexademical to Decimal. Target the result by updating the response in the then block.

1
 result = response.data.result;
2
 console.log(hexToDec(result));

The result will be returned as a number in the console:

1
179

Once you complete this tutorial, let us know how your experience was or if you have any feedback by tagging us on Twitter @Alchemy! 🎉