@ethereumjs/common
Advanced tools
@ethereumjs/common is a JavaScript library that provides common Ethereum constants, parameters, and functions. It is used to define and manage chain and hardfork parameters, making it easier to work with different Ethereum networks and their respective upgrades.
Chain and Hardfork Parameters
This feature allows you to define and manage chain and hardfork parameters. The code sample demonstrates how to create a Common instance for the Ethereum mainnet with the 'istanbul' hardfork.
const Common = require('@ethereumjs/common').default;
const mainnetCommon = new Common({ chain: 'mainnet', hardfork: 'istanbul' });
console.log(mainnetCommon.chainName()); // 'mainnet'
console.log(mainnetCommon.hardfork()); // 'istanbul'Custom Chains
This feature allows you to define custom chain parameters. The code sample demonstrates how to create a Common instance for a custom chain with specific chain and network IDs.
const Common = require('@ethereumjs/common').default;
const customChainParams = { name: 'custom', chainId: 1234, networkId: 1234 };
const customCommon = Common.forCustomChain('mainnet', customChainParams, 'istanbul');
console.log(customCommon.chainId()); // 1234EIP Activation
This feature allows you to check if a specific Ethereum Improvement Proposal (EIP) is activated for a given hardfork. The code sample demonstrates how to check if EIP-1559 is activated for the 'berlin' hardfork.
const Common = require('@ethereumjs/common').default;
const common = new Common({ chain: 'mainnet', hardfork: 'berlin' });
console.log(common.isActivatedEIP(1559)); // true or false depending on the EIP and hardforkweb3.js is a collection of libraries that allow you to interact with a local or remote Ethereum node using HTTP, IPC, or WebSocket. While it provides broader functionality for interacting with the Ethereum blockchain, it does not focus specifically on chain and hardfork parameters like @ethereumjs/common.
ethers.js is a library for interacting with the Ethereum blockchain and its ecosystem. It provides utilities for signing transactions, interacting with smart contracts, and more. Similar to web3.js, it offers a broader range of functionalities but does not specialize in chain and hardfork parameters.
ethjs is a highly modular, lightweight library for interacting with the Ethereum blockchain. It provides basic functionalities for sending transactions, interacting with contracts, and more. However, it does not offer the same level of detail for chain and hardfork parameters as @ethereumjs/common.
| Resources common to all EthereumJS implementations. |
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Note: this README reflects the state of the library from v2.0.0 onwards. See README from the standalone repository for an introduction on the last preceding release.
To obtain the latest version, simply require the project using npm:
npm install @ethereumjs/common
import (ESM, TypeScript):
import { Chain, Common, Hardfork } from '@ethereumjs/common
require (CommonJS, Node.js):
const { Common, Chain, Hardfork } = require('@ethereumjs/common')
All parameters can be accessed through the Common class, instantiated with an object containing either the chain (e.g. 'Chain.Mainnet') or the chain together with a specific hardfork provided:
// With enums:
const common = new Common({ chain: Chain.Mainnet, hardfork: Hardfork.London })
// (also possible with directly passing in strings:)
const common = new Common({ chain: 'mainnet', hardfork: 'london' })
If no hardfork is provided, the common is initialized with the default hardfork.
Current DEFAULT_HARDFORK: Hardfork.Merge
Here are some simple usage examples:
// Instantiate with the chain (and the default hardfork)
let c = new Common({ chain: Chain.Ropsten })
c.param('gasPrices', 'ecAddGas') // 500
// Chain and hardfork provided
c = new Common({ chain: Chain.Ropsten, hardfork: Hardfork.Byzantium })
c.param('pow', 'minerReward') // 3000000000000000000
// Get bootstrap nodes for chain/network
c.bootstrapNodes() // Array with current nodes
// Instantiate with an EIP activated
c = new Common({ chain: Chain.Mainnet, eips: [2537] })
See the API documentation for a full list of functions for accessing specific chain and
depending hardfork parameters. There are also additional helper functions like
paramByBlock (topic, name, blockNumber) or hardforkIsActiveOnBlock (hardfork, blockNumber)
to ease blockNumber based access to parameters.
Generated TypeDoc API Documentation
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.
The Common class is implemented as an EventEmitter and is emitting the following events
on which you can react within your code:
| Event | Description |
|---|---|
hardforkChanged | Emitted when a hardfork change occurs in the Common object |
The chain can be set in the constructor like this:
const c = new Common({ chain: Chain.Ropsten })
Supported chains:
mainnet (Chain.Mainnet)ropsten (Chain.Ropsten)rinkeby (Chain.Rinkeby)goerli (Chain.Goerli)sepolia (Chain.Sepolia) (v2.6.1+)The following chain-specific parameters are provided:
namechainIdnetworkIdconsensusType (e.g. pow or poa)consensusAlgorithm (e.g. ethash or clique)consensusConfig (depends on consensusAlgorithm, e.g. period and epoch for clique)genesis block header valueshardforks block numbersbootstrapNodes listdnsNetworks list (EIP-1459-compliant list of DNS networks for peer discovery)To get an overview of the different parameters have a look at one of the chain-specific
files like mainnet.json in the chains directory, or to the Chain type in ./src/types.ts.
There are two distinct APIs available for setting up custom(ized) chains.
There is a dedicated Common.custom() static constructor which allows for an easy instantiation of a Common instance with somewhat adopted chain parameters, with the main use case to adopt on instantiating with a deviating chain ID (you can use this to adopt other chain parameters as well though). Instantiating a custom common instance with its own chain ID and inheriting all other parameters from mainnet can now be as easily done as:
const common = Common.custom({ chainId: 1234 })
The custom() method also takes a string as a first input (instead of a dictionary). This can be used in combination with the CustomChain enum dict which allows for the selection of predefined supported custom chains for an easier Common setup of these supported chains:
const common = Common.custom(CustomChain.ArbitrumRinkebyTestnet)
The following custom chains are currently supported:
PolygonMainnetPolygonMumbaiArbitrumRinkebyTestnetxDaiChainOptimisticKovanOptimisticEthereumCommon instances created with this simplified custom() constructor can't be used in all usage contexts (the HF configuration is very likely not matching the actual chain) but can be useful for specific use cases, e.g. for sending a tx with @ethereumjs/tx to an L2 network (see the Tx library README for a complete usage example).
If you want to initialize a Common instance with a single custom chain which is then directly activated
you can pass a dictionary - conforming to the parameter format described above - with your custom chain
values to the constructor using the chain parameter or the setChain() method, here is some example:
import myCustomChain from './[PATH]/myCustomChain.json'
const common = new Common({ chain: myCustomChain })
A second way for custom chain initialization is to use the customChains constructor option. This
option comes with more flexibility and allows for an arbitrary number of custom chains to be initialized on
a common instance in addition to the already supported ones. It also allows for an activation-independent
initialization, so you can add your chains by adding to the customChains array and either directly
use the chain option to activate one of the custom chains passed or activate a build in chain
(e.g. mainnet) and switch to other chains - including the custom ones - by using Common.setChain().
import myCustomChain1 from './[PATH]/myCustomChain1.json'
import myCustomChain2 from './[PATH]/myCustomChain2.json'
// Add two custom chains, initial mainnet activation
const common1 = new Common({ chain: 'mainnet', customChains: [myCustomChain1, myCustomChain2] })
// Somewhat later down the road...
common1.setChain('customChain1')
// Add two custom chains, activate customChain1
const common1 = new Common({
chain: 'customChain1',
customChains: [myCustomChain1, myCustomChain2],
})
Starting with v3 custom genesis states should be passed to the Blockchain library directly.
For lots of custom chains (for e.g. devnets and testnets), you might come across a genesis json config which has both config specification for the chain as well as the genesis state specification. You can derive the common from such configuration in the following manner:
import { Common } from '@ethereumjs/common'
// Load geth genesis json file into lets say `genesisJson` and optional `chain` and `genesisHash`
const common = Common.fromGethGenesis(genesisJson, { chain: 'customChain', genesisHash })
// If you don't have `genesisHash` while initiating common, you can later configure common (for e.g.
// post calculating it via `blockchain`)
common.setForkHashes(genesisHash)
The hardfork can be set in constructor like this:
import { Chain, Common, Hardfork } from '@ethereumjs/common'
const c = new Common({ chain: Chain.Ropsten, hardfork: Hardfork.Byzantium })
There are currently parameter changes by the following past and future hardfork by the library supported:
chainstart (Hardfork.Chainstart)homestead (Hardfork.Homestead)dao (Hardfork.Dao)tangerineWhistle (Hardfork.TangerineWhistle)spuriousDragon (Hardfork.SpuriousDragon)byzantium (Hardfork.Byzantium)constantinople (Hardfork.Constantinople)petersburg (Hardfork.Petersburg) (aka constantinopleFix, apply together with constantinople)istanbul (Hardfork.Instanbul)muirGlacier (Hardfork.MuirGlacier)berlin (Hardfork.Berlin) (since v2.2.0)london (Hardfork.London) (since v2.4.0)merge (Hardfork.Merge) (DEFAULT_HARDFORK) (since v2.5.0)shanghai (Hardfork.Shanghai) (since v3.1.0)The next upcoming HF Hardfork.Cancun is currently not yet supported by this library.
For hardfork-specific parameter access with the param() and paramByBlock() functions
you can use the following topics:
gasConfiggasPricesvmpowshardingSee one of the hardfork files like byzantium.json in the hardforks directory
for an overview. For consistency, the chain start (chainstart) is considered an own
hardfork.
The hardfork-specific json files only contain the deltas from chainstart and
shouldn't be accessed directly until you have a specific reason for it.
Starting with the v2.0.0 release of the library, EIPs are now native citizens within the library
and can be activated like this:
const c = new Common({ chain: Chain.Mainnet, eips: [2537] })
The following EIPs are currently supported:
experimental)experimental)experimental)experimental)You can use common.bootstrapNodes() function to get nodes for a specific chain/network.
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.
FAQs
Resources common to all Ethereum implementations
We found that @ethereumjs/common demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 4 open source maintainers collaborating on the project.
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