> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chainstack.com/llms.txt
> Use this file to discover all available pages before exploring further.
# eth_newFilter | Cronos
> Cronos API method that generates a filter object based on the filter parameters. Available on Cronos via Chainstack JSON-RPC nodes.
Cronos API method that generates a filter object based on the filter parameters. It returns a filter ID, which can be used to retrieve the filter results using the `eth_getFilterChanges` method. By creating a filter for specific events, developers can receive notifications when those events occur and use them to trigger actions in their applications.
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## Parameters
* `object` — the filter parameters:
* `fromBlock` — (optional, default: `latest`) integer that specifies the starting block number from which the logs should be fetched.
* `toBlock` — (optional, default: `latest`) integer that specifies the ending block number until which the logs should be fetched.
* `address` — (optional) the contract address from which the logs should be fetched. It can be a single address or an array of addresses.
* `topics` — (optional) an array of `DATA` topics. The event topics for which the logs should be fetched. It can be a single topic or an array of topics.
* `blockhash` — (optional) the hash of the specific block. Limits logs to a specific block with a 32-byte hash value. It takes precedence over `fromBlock` and `toBlock`.
**Possible tags forfromBlockandtoBlock**
* `latest` — the most recent block in the blockchain and the current state of the blockchain at the most recent block.
* `safe` — the block that received justification from the beacon chain. Although this block could be involved in a chain reorganization, it would necessitate either a coordinated attack by the majority of validators or an instance of severe propagation latency.
* `finalized` — the block accepted as canonical by more than 2/3 of the validators. A chain reorganization is extremely unlikely, and it would require at least 1/3 of the staked ETH to be burned.
* `earliest` — the earliest available or genesis block.
* `pending` — the pending state and transactions block. The current state of transactions that have been broadcast to the network but have not yet been included in a block.
See the [default block parameter](https://ethereum.org/en/developers/docs/apis/json-rpc/#default-block) and [How The Merge Impacts Ethereum’s Application Layer](https://blog.ethereum.org/2021/11/29/how-the-merge-impacts-app-layer).
## 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 is automatically deleted if not polled within a certain time (5 minutes by default).
## `eth_newFilter` code examples
Note that the `web3.eth.filter` methods have been deprecated and replaced with the `web3.eth.subscribe` in web3.js. See [web3.js subscriptions](/reference/ethereum-web3js-subscriptions-methods).
```javascript ethers.js theme={"system"}
const ethers = require('ethers');
const NODE_URL = "CHAINSTACK_NODE_URL";
const provider = new ethers.JsonRpcProvider(NODE_URL);
const filter = {
toBlock: 'latest',
address: '0x5C7F8A570d578ED84E63fdFA7b1eE72dEae1AE23',
topics: ['0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef']
};
const createFilter = async () => {
try {
const filterId = await provider.send('eth_newFilter', [filter]);
console.log(filterId); // the filter ID returned by eth_newFilter
return filterId
} catch (error) {
console.log(error);
}
};
createFilter();
```
```python web3.py theme={"system"}
const ethers = require('ethers');
const NODE_URL = "CHAINSTACK_NODE_URL";
const provider = new ethers.JsonRpcProvider(NODE_URL);
const filter = {
toBlock: 'latest',
address: '0x5C0x5C7F8A570d578ED84E63fdFA7b1eE72dEae1AE23'
topics: ['0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef']
};
const createFilter = async () => {
try {
const filterId = await provider.send('eth_newFilter', [filter]);
console.log(filterId); // the filter ID returned by eth_newFilter
return filterId
} catch (error) {
console.log(error);
}
};
createFilter();
```
## Use case
You can use `eth_newFilter` to create a filter for a specific action on a smart contract, for example, to monitor the transfer transactions from the [Wrapped CRO token](https://cronoscan.com/token/0x5c7f8a570d578ed84e63fdfa7b1ee72deae1ae23).
The idea is to create a filter using the `eth_newFilter` method to monitor an ERC-20 smart contract, WCRO in this case.
## OpenAPI
````yaml /openapi/cronos_node_api/eth_newFilter.json POST /b9b0fb92029d58b396139a9e89cf479b
openapi: 3.0.0
info:
title: Cronos Node API
version: 1.0.0
description: This is an API for interacting with a Cronos node.
servers:
- url: https://nd-907-114-772.p2pify.com
security: []
paths:
/b9b0fb92029d58b396139a9e89cf479b:
post:
tags:
- logs
summary: eth_newFilter
operationId: newFilter
requestBody:
required: true
content:
application/json:
schema:
type: object
properties:
method:
type: string
default: eth_newFilter
params:
type: array
items:
type: object
properties:
fromBlock:
type: string
title: from block
description: >-
The block number or tag to start searching for logs
from.
default: latest
address:
type: string
title: smart contract address
description: The contract address to retrieve the logs for.
topics:
type: array
title: topics
items:
type: string
description: >-
An array of 32-byte topics to filter for. Each topic
is treated as an OR condition.
default:
- fromBlock: latest
address: '0x5C7F8A570d578ED84E63fdFA7b1eE72dEae1AE23'
topics:
- >-
0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef
id:
type: integer
default: 1
jsonrpc:
type: string
default: '2.0'
responses:
'200':
description: The filter ID.
content:
application/json:
schema:
type: object
properties:
jsonrpc:
type: string
id:
type: integer
result:
type: string
````