@ethereumjs/tx

What is @ethereumjs/tx?

@ethereumjs/tx is a library for creating, signing, and serializing Ethereum transactions. It is part of the EthereumJS suite of tools and is widely used for handling Ethereum transactions in a programmatic way.

What are @ethereumjs/tx's main functionalities?

Creating a Transaction

This feature allows you to create a new Ethereum transaction by providing the necessary transaction data such as nonce, gas price, gas limit, recipient address, value, and data.

const { Transaction } = require('@ethereumjs/tx');
const txData = {
  nonce: '0x00',
  gasPrice: '0x09184e72a000',
  gasLimit: '0x2710',
  to: '0x0000000000000000000000000000000000000000',
  value: '0x00',
  data: '0x00'
};
const tx = Transaction.fromTxData(txData);

Signing a Transaction

This feature allows you to sign a transaction using a private key. The signed transaction can then be sent to the Ethereum network.

const { Transaction } = require('@ethereumjs/tx');
const { privateToAddress, toBuffer } = require('ethereumjs-util');
const privateKey = Buffer.from('your_private_key', 'hex');
const txData = { /* transaction data */ };
const tx = Transaction.fromTxData(txData);
const signedTx = tx.sign(privateKey);

Serializing a Transaction

This feature allows you to serialize a transaction into a format that can be sent over the network or stored for later use.

const { Transaction } = require('@ethereumjs/tx');
const txData = { /* transaction data */ };
const tx = Transaction.fromTxData(txData);
const serializedTx = tx.serialize();

Other packages similar to @ethereumjs/tx

ethers

The ethers.js library is a complete and compact library for interacting with the Ethereum blockchain and its ecosystem. It provides similar functionalities for creating, signing, and sending transactions, but also includes additional features like interacting with smart contracts, ENS, and more.

web3

Web3.js is a collection of libraries that allow you to interact with a local or remote Ethereum node using HTTP, IPC, or WebSocket. It provides comprehensive functionalities for creating, signing, and sending transactions, as well as interacting with smart contracts and other Ethereum network features.

README

@ethereumjs/tx

Implements schema and functions related to Ethereum's transaction.

Note: this README reflects the state of the library from v3.0.0 onwards. See README from the standalone repository for an introduction on the last preceding release.

INSTALL

npm install @ethereumjs/tx

USAGE

Setup

Static Constructor Methods

To instantiate a tx it is not recommended to use the constructor directly. Instead each tx type comes with the following set of static constructor methods which helps on instantiation depending on the input data format:

• public static fromTxData(txData: TxData, opts: TxOptions = {}): instantiate from a data dictionary
• public static fromSerializedTx(serialized: Buffer, opts: TxOptions = {}): instantiate from a serialized tx
• public static fromValuesArray(values: Buffer[], opts: TxOptions = {}): instantiate from a values array

See one of the code examples on the tx types below on how to use.

All types of transaction objects are frozen with Object.freeze() which gives you enhanced security and consistency properties when working with the instantiated object. This behavior can be modified using the freeze option in the constructor if needed.

Chain and Hardfork Support

The Transaction constructor receives a parameter of an @ethereumjs/common object that lets you specify the chain and hardfork to be used. If there is no Common provided the chain ID provided as a paramter on typed tx or the chain ID derived from the v value on signed EIP-155 conforming legacy txs will be taken (introduced in v3.2.1). In other cases the chain defaults to mainnet.

Base default HF (determined by Common): london

Starting with v3.2.1 the tx library now deviates from the default HF for typed tx using the following rule: "The default HF is the default HF from Common if the tx type is active on that HF. Otherwise it is set to the first greater HF where the tx is active."

Supported Hardforks:

Hardfork	Introduced	Description
london	v3.2.0	EIP-1559 Transactions
berlin	v3.1.0	EIP-2718 Typed Transactions, Optional Access Lists Tx Type EIP-2930
muirGlacier	v2.1.2	-
istanbul	v2.1.1	Support for reduced non-zero call data gas prices (EIP-2028)
spuriousDragon	v2.0.0	EIP-155 replay protection (disable by setting HF pre-spuriousDragon)

Standalone EIPs

The following "standalone" EIPs are supported by the library can be manually activated using a respectively initialized Common instance, e.g.:

const common = new Common({ chain: Chain.Mainnet, hardfork: Hardfork.London, eips: [3860] })

• EIP-3860: Limit and meter initcode (experimental)

Transaction Types

This library supports the following transaction types (EIP-2718):

• FeeMarketEIP1559Transaction (EIP-1559, gas fee market)
• AccessListEIP2930Transaction (EIP-2930, optional access lists)
• Transaction, the Ethereum standard tx up to berlin, now referred to as legacy txs with the introduction of tx types

Gas Fee Market Transactions (EIP-1559)

• Class: FeeMarketEIP1559Transaction
• Activation: london
• Type: 2

This is the recommended tx type starting with the activation of the london HF, see the following code snipped for an example on how to instantiate:

import { Chain, Common, Hardfork } from '@ethereumjs/common'
import { FeeMarketEIP1559Transaction } from '@ethereumjs/tx'

const common = new Common({ chain: Chain.Mainnet, hardfork: Hardfork.London })

const txData = {
  data: '0x1a8451e600000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000',
  gasLimit: '0x02625a00',
  maxPriorityFeePerGas: '0x01',
  maxFeePerGas: '0xff',
  nonce: '0x00',
  to: '0xcccccccccccccccccccccccccccccccccccccccc',
  value: '0x0186a0',
  v: '0x01',
  r: '0xafb6e247b1c490e284053c87ab5f6b59e219d51f743f7a4d83e400782bc7e4b9',
  s: '0x479a268e0e0acd4de3f1e28e4fac2a6b32a4195e8dfa9d19147abe8807aa6f64',
  chainId: '0x01',
  accessList: [],
  type: '0x02',
}

const tx = FeeMarketEIP1559Transaction.fromTxData(txData, { common })

Access List Transactions (EIP-2930)

• Class: AccessListEIP2930Transaction
• Activation: berlin
• Type: 1

This transaction type has been introduced along the berlin HF. See the following code snipped for an example on how to instantiate:

import { Chain, Common, Hardfork } from '@ethereumjs/common'
import { AccessListEIP2930Transaction } from '@ethereumjs/tx'

const common = new Common({ chain: Chain.Mainnet, hardfork: Hardfork.Berlin })

const txData = {
  data: '0x1a8451e600000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000',
  gasLimit: '0x02625a00',
  gasPrice: '0x01',
  nonce: '0x00',
  to: '0xcccccccccccccccccccccccccccccccccccccccc',
  value: '0x0186a0',
  v: '0x01',
  r: '0xafb6e247b1c490e284053c87ab5f6b59e219d51f743f7a4d83e400782bc7e4b9',
  s: '0x479a268e0e0acd4de3f1e28e4fac2a6b32a4195e8dfa9d19147abe8807aa6f64',
  chainId: '0x01',
  accessList: [
    {
      address: '0x0000000000000000000000000000000000000101',
      storageKeys: [
        '0x0000000000000000000000000000000000000000000000000000000000000000',
        '0x00000000000000000000000000000000000000000000000000000000000060a7',
      ],
    },
  ],
  type: '0x01',
}

const tx = AccessListEIP2930Transaction.fromTxData(txData, { common })

For generating access lists from tx data based on a certain network state there is a reportAccessList option on the Vm.runTx() method of the @ethereumjs/vm TypeScript VM implementation.

Legacy Transactions

• Class: Transaction
• Activation: chainstart (with modifications along the road, see HF section below)
• Type: 0 (internal)

Legacy transaction are still valid transaction within Ethereum mainnet but will likely be deprecated at some point. See this example script or the following code example on how to use.

import { Chain, Common, Hardfork } from '@ethereumjs/common'
import { Transaction } from '@ethereumjs/tx'

const txParams = {
  nonce: '0x00',
  gasPrice: '0x09184e72a000',
  gasLimit: '0x2710',
  to: '0x0000000000000000000000000000000000000000',
  value: '0x00',
  data: '0x7f7465737432000000000000000000000000000000000000000000000000000000600057',
}

const common = new Common({ chain: Chain.Mainnet, hardfork: Hardfork.Istanbul })
const tx = Transaction.fromTxData(txParams, { common })

const privateKey = Buffer.from(
  'e331b6d69882b4cb4ea581d88e0b604039a3de5967688d3dcffdd2270c0fd109',
  'hex'
)

const signedTx = tx.sign(privateKey)

const serializedTx = signedTx.serialize()

Transaction Factory

If you only know on runtime which tx type will be used within your code or if you want to keep your code transparent to tx types, this library comes with a TransactionFactory for your convenience which can be used as follows:

import { Chain, Common, Hardfork } from '@ethereumjs/common'
import { TransactionFactory } from '@ethereumjs/tx'

const common = new Common({ chain: Chain.Mainnet, hardfork: Hardfork.Berlin })

const txData = {} // Use data from the different tx type examples
const tx = TransactionFactory.fromTxData(txData, { common })

if (tx.supports(Capability.EIP2930AccessLists)) {
  // Do something which only makes sense for txs with support for access lists
}

The correct tx type class for instantiation will then be chosen on runtime based on the data provided as an input.

TransactionFactory supports the following static constructor methods:

• public static fromTxData(txData: TxData | AccessListEIP2930TxData, txOptions: TxOptions = {}): TypedTransaction
• public static fromSerializedData(data: Buffer, txOptions: TxOptions = {}): TypedTransaction
• public static fromBlockBodyData(data: Buffer | Buffer[], txOptions: TxOptions = {})

Sending a Transaction

L2 Support

This library has been tested to work with various L2 networks (v3.3.0+). All predefined supported custom chains introduced with Common v2.4.0 or higher are supported, the following is a simple example to send a tx to the xDai chain:

import { Transaction } from '@ethereumjs/tx'
import { Common } from '@ethereumjs/common'

const from = 'PUBLIC_KEY'
const PRIV_KEY = process.argv[2]
const to = 'DESTINATION_ETHEREUM_ADDRESS'

const common = Common.custom(CustomChain.xDaiChain)

const txData = {
  from,
  nonce: 0,
  gasPrice: 1000000000,
  gasLimit: 21000,
  to,
  value: 1,
}

const tx = Transaction.fromTxData(txData, { common })
const signedTx = tx.sign(Buffer.from(PRIV_KEY, 'hex'))

The following L2 networks have been tested to work with @ethereumjs/tx, see usage examples as well as some notes on pecularities in the issues linked below:

L2 Network	Common name	Issue
Arbitrum Rinkeby Testnet	CustomChain.ArbitrumRinkebyTestnet	#1290
Polygon Mainnet	CustomChain.PolygonMainnet	#1289
Polygon Mumbai Testnet	CustomChain.PolygonMumbai	#1289
xDai Chain	Common.xDaiChain	#1323
Optimistic Kovan	Common.OptimisticKovan	#1554
Optimistic Ethereum	Common.OptimisticEthereum	#1554

Note: For Optimistic Kovan and Optimistic Ethereum, the London hardfork has not been implemented so transactions submitted with a baseFee will revert. The London hardfork is targeted to implement on Optimism in Q1.22.

For a non-predefined custom chain it is also possible to just provide a chain ID as well as other parameters to Common:

const common = Common.custom({ chainId: 1234 })

Special Topics

Signing with a hardware or external wallet

To sign a tx with a hardware or external wallet use tx.getMessageToSign(false) to return an EIP-155 compliant unsigned tx.

A legacy transaction will return a Buffer list of the values, and a Typed Transaction (EIP-2718) will return the serialized output.

Here is an example of signing txs with @ledgerhq/hw-app-eth as of v6.5.0:

import { Transaction, FeeMarketEIP1559Transaction } from '@ethereumjs/tx'
import { Chain, Common } from '@ethereumjs/common'
import { bufArrToArr } from '@ethereumjs/util'
import { RLP } from 'rlp'
import Eth from '@ledgerhq/hw-app-eth'

const eth = new Eth(transport)
const common = new Common({ chain: Chain.Rinkeby })

let txData: any = { value: 1 }
let tx: Transaction | FeeMarketEIP1559Transaction
let unsignedTx: Buffer[] | Buffer
let signedTx: typeof tx
const bip32Path = "44'/60'/0'/0/0"

const run = async () => {
  // Signing a legacy tx
  tx = Transaction.fromTxData(txData, { common })
  unsignedTx = tx.getMessageToSign(false)
  unsignedTx = Buffer.from(RLP.encode(bufArrToArr(unsignedTx))) // ledger signTransaction API expects it to be serialized
  let { v, r, s } = await eth.signTransaction(bip32Path, unsignedTx)
  txData = { ...txData, v, r, s }
  signedTx = Transaction.fromTxData(txData, { common })
  let from = signedTx.getSenderAddress().toString()
  console.log(`signedTx: 0x${signedTx.serialize().toString('hex')}\nfrom: ${from}`)

  // Signing a 1559 tx
  txData = { value: 1 }
  tx = FeeMarketEIP1559Transaction.fromTxData(txData, { common })
  unsignedTx = tx.getMessageToSign(false)
  ;({ v, r, s } = await eth.signTransaction(bip32Path, unsignedTx)) // this syntax is: object destructuring - assignment without declaration
  txData = { ...txData, v, r, s }
  signedTx = FeeMarketEIP1559Transaction.fromTxData(txData, { common })
  from = signedTx.getSenderAddress().toString()
  console.log(`signedTx: ${signedTx.serialize().toString('hex')}\nfrom: ${from}`)
}

run()

Fake Transaction

Creating a fake transaction for use in e.g. VM.runTx() is simple, just overwrite getSenderAddress() with a custom Address like so:

import { Address } from '@ethereumjs/util'
import { Transaction } from '@ethereumjs/tx'

_getFakeTransaction(txParams: TxParams): Transaction {
  const from = Address.fromString(txParams.from)
  delete txParams.from

  const opts = { common: this._common, freeze: false }
  const tx = Transaction.fromTxData(txParams, opts)

  // override getSenderAddress
  tx.getSenderAddress = () => { return from }

  return tx
}

API

Docs

Generated TypeDoc API Documentation

BigInt Support

Starting with v4 the usage of BN.js for big numbers has been removed from the library and replaced with the usage of the native JS BigInt data type (introduced in ES2020).

Please note that number-related API signatures have changed along with this version update and the minimal build target has been updated to ES2020.

EthereumJS

See our organizational documentation for an introduction to EthereumJS as well as information on current standards and best practices.

If you want to join for work or do improvements on the libraries have a look at our contribution guidelines.

LICENSE

MPL-2.0