> ## Documentation Index
> Fetch the complete documentation index at: https://docs.pulsy.app/llms.txt
> Use this file to discover all available pages before exploring further.

# JavaScript Modules

> See the JavaScript helpers available inside filters.

# JavaScript Modules

In the current runtime, filters are authored in JavaScript and can use a small set of bundled modules. These modules are available through `require(...)` inside the filter.

Only modules registered by the runtime can be imported. A filter cannot install packages dynamically or import arbitrary npm dependencies.

## `ethers`

Use `ethers` for EVM-specific parsing, encoding, decoding, and unit conversion.

```javascript theme={null}
const ethers = require("ethers");

function main(stream) {
  // 0xde0b6b3a7640000 is 1 ETH in wei, encoded as a hex quantity.
  const valueEth = ethers.formatEther("0xde0b6b3a7640000");

  return {
    metadata: stream.metadata,
    valueEth
  };
}
```

Common uses:

* Build an ABI interface with `new ethers.Interface(...)`.
* Parse event logs with `iface.parseLog(...)`.
* Read an event topic with `iface.getEvent("Transfer").topicHash`.
* Convert native token units with `ethers.parseEther(...)` and `ethers.formatEther(...)`.
* Convert token units with `ethers.parseUnits(...)` and `ethers.formatUnits(...)`.
* Work with large integer values safely through `BigInt`-compatible values.

Use `ethers` when the feed needs low-level EVM handling or precise token amount conversion.

## `@atria/sdk`

Use `@atria/sdk` for Atria-provided helpers that sit above raw `ethers` usage.

```javascript theme={null}
const atria = require("@atria/sdk");

function main(stream) {
  const decoded = atria.evm.decodeEVMLogs(stream.logs || [], [
    [
      "event Transfer(address indexed from, address indexed to, uint256 value)"
    ]
  ]);

  if (decoded.length === 0) return null;

  return {
    metadata: stream.metadata,
    transfers: decoded
  };
}
```

Current helper:

* `atria.evm.decodeEVMLogs(data, abis)`

`decodeEVMLogs` accepts either an array of logs or an array of receipt-like objects with `logs`. It tries to decode each log against the provided ABIs. Logs that do not match are ignored. Decoded logs include a `decodedLog` object with `name`, `signature`, and named `args`.

Use `@atria/sdk` when you want a feed to decode EVM logs without writing the full parse loop yourself.

## `@atria/kv`

Use `@atria/kv` for lightweight feed state when KV access is enabled for the feed runtime.

```javascript theme={null}
const kv = require("@atria/kv");

async function main(stream) {
  const seen = kv.bucket("seen-blocks");
  const key = stream.metadata.blockNumber;

  if (await seen.get(key)) return null;

  await seen.add(key, true);

  return {
    metadata: stream.metadata,
    firstSeen: key
  };
}
```

Use KV for compact workflow state, lookup values, and simple deduplication. Do not use it as a warehouse, analytics store, or large event archive.

For the full list of bucket operations, see [KV storage](/atria/core-concepts/kv-storage).

## Module Boundaries

Filters can only import the modules that Atria bundles into the runtime. For example, `require("ethers")` works, but `require("lodash")` fails unless that module has been added to the runtime. If you need a small helper, define it in the filter file itself.

See [filters](/atria/core-concepts/filters), [KV storage](/atria/core-concepts/kv-storage), and [security and sandboxing](/atria/architecture/security-and-sandboxing).