vm

@ethereumjs/vm

Execution Context for the Ethereum EVM Implementation.

This package provides an Ethereum mainnet compatible execution context for the @ethereumjs/evm EVM implementation.

So beyond bytecode processing this package allows to run or build new Ethereum blocks or single transactions and update a blockchain state accordingly.

Note that up till v5 this package also was the bundled package for the EVM implementation itself.

Installation

To obtain the latest version, simply require the project using npm:

npm install @ethereumjs/vm

Note: Starting with the Dencun hardfork EIP-4844 related functionality has become an integrated part of the EVM functionality with the activation of the point evaluation precompile. For this precompile to work a separate installation of the KGZ library is necessary (we decided not to bundle due to large bundle sizes), see KZG Setup for instructions.

Usage

Running a Transaction

// ./examples/runTx.ts

import { Common, Hardfork, Mainnet } from '@ethereumjs/common'
import { createLegacyTx } from '@ethereumjs/tx'
import { createZeroAddress } from '@ethereumjs/util'
import { createVM, runTx } from '@ethereumjs/vm'

const main = async () => {
  const common = new Common({ chain: Mainnet, hardfork: Hardfork.Shanghai })
  const vm = await createVM({ common })

  const tx = createLegacyTx({
    gasLimit: BigInt(21000),
    gasPrice: BigInt(1000000000),
    value: BigInt(1),
    to: createZeroAddress(),
    v: BigInt(37),
    r: BigInt('62886504200765677832366398998081608852310526822767264927793100349258111544447'),
    s: BigInt('21948396863567062449199529794141973192314514851405455194940751428901681436138'),
  })
  const res = await runTx(vm, { tx, skipBalance: true })
  console.log(res.totalGasSpent) // 21000n - gas cost for simple ETH transfer
}

void main()

Additionally to the VM.runTx() method there is an API method VM.runBlock() which allows to run the whole block and execute all included transactions along.

Building a Block

The VM package can also be used to construct a new valid block by executing and then integrating txs one-by-one.

The following non-complete example gives some illustration on how to use the Block Builder API:

// ./examples/buildBlock.ts

import { createBlock } from '@ethereumjs/block'
import { Common, Mainnet } from '@ethereumjs/common'
import { createLegacyTx } from '@ethereumjs/tx'
import { Account, bytesToHex, createAddressFromPrivateKey, hexToBytes } from '@ethereumjs/util'
import { buildBlock, createVM } from '@ethereumjs/vm'

const main = async () => {
  const common = new Common({ chain: Mainnet })
  const vm = await createVM({ common })

  const parentBlock = createBlock(
    { header: { number: 1n } },
    { skipConsensusFormatValidation: true },
  )
  const headerData = {
    number: 2n,
  }
  const blockBuilder = await buildBlock(vm, {
    parentBlock, // the parent @ethereumjs/block Block
    headerData, // header values for the new block
    blockOpts: {
      calcDifficultyFromHeader: parentBlock.header,
      freeze: false,
      skipConsensusFormatValidation: true,
      putBlockIntoBlockchain: false,
    },
  })

  const pk = hexToBytes('0x26f81cbcffd3d23eace0bb4eac5274bb2f576d310ee85318b5428bf9a71fc89a')
  const address = createAddressFromPrivateKey(pk)
  const account = new Account(0n, 0xfffffffffn)
  await vm.stateManager.putAccount(address, account) // create a sending account and give it a big balance
  const tx = createLegacyTx({ gasLimit: 0xffffff, gasPrice: 75n }).sign(pk)
  await blockBuilder.addTransaction(tx)

  // Add more transactions

  const { block } = await blockBuilder.build()
  console.log(`Built a block with hash ${bytesToHex(block.hash())}`)
}

void main()

WASM Crypto Support

This library by default uses JavaScript implementations for the basic standard crypto primitives like hashing or signature verification (for included txs). See @ethereumjs/common README for instructions on how to replace with e.g. a more performant WASM implementation by using a shared common instance.

Example

See the examples folder for different meaningful examples on how to use the VM package and invoke certain aspects of it, e.g. running a complete block, a certain tx or using event listeners, among others. Some noteworthy examples to point out:

1. ./examples/run-blockchain: Loads tests data, including accounts and blocks, and runs all of them in the VM.
2. ./examples/run-solidity-contract: Compiles a Solidity contract, and calls constant and non-constant functions.

Browser

We provide hybrid ESM/CJS builds for all our libraries. With the v10 breaking release round from Spring 2025, all libraries are "pure-JS" by default and we have eliminated all hard-wired WASM code. Additionally we have substantially lowered the bundle sizes, reduced the number of dependencies, and cut out all usages of Node.js-specific primitives (like the Node.js event emitter).

It is easily possible to run a browser build of one of the EthereumJS libraries within a modern browser using the provided ESM build. For a setup example see ./examples/browser.html.

API

Docs

For documentation on VM instantiation, exposed API and emitted events see generated API docs.

Hybrid CJS/ESM Builds

With the breaking releases from Summer 2023 we have started to ship our libraries with both CommonJS (cjs folder) and ESM builds (esm folder), see package.json for the detailed setup.

If you use an ES6-style import in your code files from the ESM build will be used:

import { EthereumJSClass } from '@ethereumjs/[PACKAGE_NAME]'

If you use Node.js specific require, the CJS build will be used:

const { EthereumJSClass } = require('@ethereumjs/[PACKAGE_NAME]')

Using ESM will give you additional advantages over CJS beyond browser usage like static code analysis / Tree Shaking which CJS can not provide.

Architecture

VM/EVM Relation

Starting with the VM v6 version the inner Ethereum Virtual Machine core previously included in this library has been extracted to an own package @ethereumjs/evm.

It is still possible to access all EVM functionality through the evm property of the initialized vm object, e.g.:

vm.evm.runCode()
vm.evm.events.on('step', function (data) {
  console.log(`Opcode: ${data.opcode.name}\tStack: ${data.stack}`)
})

Note that it's now also possible to pass in an own or customized EVM instance by using the optional evm constructor option.

State and Blockchain Information

With VM v7 a previously needed EEI interface for EVM/VM communication is not needed any more and the API has been simplified, also see the respective EVM README section. Most of the EEI related logic is now either handled internally or more generic functionality being taken over by the @ethereumjs/statemanager package, with the EVM now taking in both an (optional) stateManager and blockchain argument for the constructor (which the VM passes over by default).

With VM v6 the previously included StateManager has been extracted to its own package @ethereumjs/statemanager. The StateManager package provides a unified state interface and it is now also possible to provide a modified or custom StateManager to the VM via the optional stateManager constructor option.

Setup

Chain Support

Beside the default Proof-of-Stake setup coming with the Common library default, the VM also support the execution of both Ethash/PoW and Clique/PoA blocks and transactions to allow to re-execute blocks from older hardforks or testnets.

Hardfork Support

For hardfork support see the Hardfork Support section from the underlying @ethereumjs/evm instance.

An explicit HF in the VM - which is then passed on to the inner EVM - can be set with:

// ./examples/runTx.ts#L1-L8

import { Common, Hardfork, Mainnet } from '@ethereumjs/common'
import { createLegacyTx } from '@ethereumjs/tx'
import { createZeroAddress } from '@ethereumjs/util'
import { createVM, runTx } from '@ethereumjs/vm'

const main = async () => {
  const common = new Common({ chain: Mainnet, hardfork: Hardfork.Shanghai })
  const vm = await createVM({ common })

Custom Genesis State Support

For initializing a custom genesis state you can use the genesisState constructor option in the Blockchain and VM library in a similar way this had been done in the Common library before.

// ./examples/vmWithGenesisState.ts

import { Chain } from '@ethereumjs/common'
import { getGenesis } from '@ethereumjs/genesis'
import { createAddressFromString } from '@ethereumjs/util'
import { createVM } from '@ethereumjs/vm'

const main = async () => {
  const genesisState = getGenesis(Chain.Mainnet)

  const vm = await createVM()
  await vm.stateManager.generateCanonicalGenesis!(genesisState)
  const account = await vm.stateManager.getAccount(
    createAddressFromString('0x000d836201318ec6899a67540690382780743280'),
  )

  if (account === undefined) {
    throw new Error('Account does not exist: failed to import genesis state')
  }

  console.log(
    `This balance for account 0x000d836201318ec6899a67540690382780743280 in this chain's genesis state is ${Number(
      account?.balance,
    )}`,
  )
}
void main()

Genesis state can be configured to contain both EOAs as well as (system) contracts with initial storage values set.

EIP Support

It is possible to individually activate EIP support in the VM by instantiate the Common instance passed with the respective EIPs, e.g.:

// ./examples/vmWithEIPs.ts

import { Common, Mainnet } from '@ethereumjs/common'
import { createVM } from '@ethereumjs/vm'

const main = async () => {
  const common = new Common({ chain: Mainnet, eips: [7702] })
  const vm = await createVM({ common })
  console.log(`EIP 7702 is active in the VM - ${vm.common.isActivatedEIP(7702)}`)
}
void main()

For a list with supported EIPs see the @ethereumjs/evm documentation.

EIP-4844 Shard Blob Transactions Support (Cancun)

This library supports the blob transaction type introduced with EIP-4844. EIP-4844 comes with a dedicated opcode BLOBHASH and has added a new point evaluation precompile at address 0x0a.

Note: Usage of the point evaluation precompile needs a manual KZG library installation and global initialization, see KZG Setup for instructions.

EIP-7702 EAO Code Transactions Support (Prague)

This library support the execution of EIP-7702 EOA code transactions (see tx library for full documentation) with runTx() or the wrapping runBlock() execution methods, see this test setup for a more complete example setup on how to run code from an EOA.

EIP-7685 Requests Support (Prague)

This library supports blocks including EIP-7685 requests to the consensus layer.

EIP-2935 Serve Historical Block Hashes from State (Prague)

Starting with v8.1.0 the VM supports EIP-2935 which stores the latest 8192 block hashes in the storage of a system contract.

Note that this EIP has no effect on the resolution of the BLOCKHASH opcode, which will be a separate activation taking place by the integration of EIP-7709 in a respective Verkle/Stateless hardfork.

Tracing Events

Our TypeScript VM emits events that support async listeners (using EventEmitter3).

You can subscribe to the following events:

• beforeBlock: Emits a Block right before running it.
• afterBlock: Emits AfterBlockEvent right after running a block.
• beforeTx: Emits a Transaction right before running it.
• afterTx: Emits a AfterTxEvent right after running a transaction.

Note, if subscribing to events with an async listener, specify the second parameter of your listener as a resolve function that must be called once your listener code has finished.

// ./examples/eventListener.ts#L10-L19

// Setup an event listener on the `afterTx` event
vm.events.on('afterTx', (event, resolve) => {
  console.log('asynchronous listener to afterTx', bytesToHex(event.transaction.hash()))
  // we need to call resolve() to avoid the event listener hanging
  resolve?.()
})

vm.events.on('afterTx', (event) => {
  console.log('synchronous listener to afterTx', bytesToHex(event.transaction.hash()))
})

Please note that there are additional EVM-specific events in the @ethereumjs/evm package.

Asynchronous event handlers

You can perform asynchronous operations from within an event handler and prevent the VM to keep running until they finish.

In order to do that, your event handler has to accept two arguments. The first one will be the event object, and the second one a function. The VM won't continue until you call this function.

If an exception is passed to that function, or thrown from within the handler or a function called by it, the exception will bubble into the VM and interrupt it, possibly corrupting its state. It's strongly recommended not to do that.

Synchronous event handlers

If you want to perform synchronous operations, you don't need to receive a function as the handler's second argument, nor call it.

Note that if your event handler receives multiple arguments, the second one will be the continuation function, and it must be called.

If an exception is thrown from within the handler or a function called by it, the exception will bubble into the VM and interrupt it, possibly corrupting its state. It's strongly recommended not to throw from within event handlers.

Understanding the VM

If you want to understand your VM runs we have added a hierarchically structured list of debug loggers for your convenience which can be activated in arbitrary combinations. We also use these loggers internally for development and testing. These loggers use the debug library and can be activated on the CL with DEBUG=ethjs,[Logger Selection] node [Your Script to Run].js and produce output like the following:

The following loggers are currently available:

Logger	Description
vm:block	Block operations (run txs, generating receipts, block rewards,...)
vm:tx	Transaction operations (account updates, checkpointing,...)
vm:tx:gas	Transaction gas logger
vm:state	StateManager logger

Note that there are additional EVM-specific loggers in the @ethereumjs/evm package.

Here are some examples for useful logger combinations.

Run one specific logger:

DEBUG=ethjs,vm:tx tsx test.ts

Run all loggers currently available:

DEBUG=ethjs,vm:*,vm:*:* tsx test.ts

Run only the gas loggers:

DEBUG=ethjs,vm:*:gas tsx test.ts

Excluding the state logger:

DEBUG=ethjs,vm:*,vm:*:*,-vm:state tsx test.ts

Run some specific loggers including a logger specifically logging the SSTORE executions from the VM (this is from the screenshot above):

DEBUG=ethjs,vm:tx,vm:evm,vm:ops:sstore,vm:*:gas tsx test.ts

Internal Structure

The VM processes state changes at many levels.

• runBlockchain
  • for every block, runBlock
• runBlock
  • for every tx, runTx
  • pay miner and uncles
• runTx
  • check sender balance
  • check sender nonce
  • runCall
  • transfer gas charges

TODO: this section likely needs an update.

Development

Developer documentation - currently mainly with information on testing and debugging - can be found here.

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 carry out improvements on the libraries, please review our contribution guidelines first.

License

MPL-2.0