BNB 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

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Response

• result — 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_getFilterChanges to retrieve updates
• eth_uninstallFilter to remove the filter

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eth_newBlockFilter code examples

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();

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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.