eth_newBlockFilter | Cronos

Cronos API method that creates a filter that watches for new blocks on the blockchain. It returns a filter ID, which can be used to retrieve the results using the eth_getFilterChanges method. The eth_newBlockFilter method is useful for developers who must be notified of new blocks on the blockchain in real-time.

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Parameters

  • none

Response

  • result โ€” a hexadecimal string representing the ID of the newly created filter.

The filters created are stored on the blockchain client instance. The filter fill is automatically deleted if not polled within a certain time (5 minutes by default).

Use the following methods with the filter ID:

eth_newBlockFilter code examples

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web3.eth.filter deprecation

Note that the web3.eth.filter methods have been deprecated and replaced with the web3.eth.subscribe in web3.js. See web3.js subscriptions.

const ethers = require('ethers');
const NODE_URL = "CHAINSTACK_NODE_URL";
const provider = new ethers.JsonRpcProvider(NODE_URL);

const createFilter = async () => {
  try {
    const filterId = await provider.send('eth_newBlockFilter', []);
    console.log(filterId); // the filter ID returned by eth_newFilter
    return filterId
  } catch (error) {
    console.log(error);
  }
};

createFilter();
from web3 import Web3  
node_url = "CHAINSTACK_NODE_URL" 
web3 = Web3(Web3.HTTPProvider(node_url))

def get_new_blocks():
    try:
        blocks_filter = web3.eth.filter('latest')
        return blocks_filter
    except Exception as e:
        print(e)

blocks = get_new_blocks()
filter_id = blocks.filter_id
print(filter_id)

Use case

One use case for eth_newBlockFilter in a simple DApp is to listen for new blocks and update the user interface with the latest block information.

When the DApp starts, it creates a new filter using eth_newBlockFilter to listen for new blocks. When a new block is added to the blockchain, the filter is triggered, and the DApp retrieves the latest block information using a Web3 library.

Try the eth_newBlockFilter RPC method yourself

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