Documentation Index
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Overview
BlockHeader contains all metadata for a block including Merkle roots, gas limits, timestamps, and consensus-related fields. The block hash is computed from RLP(header).
import * as BlockHeader from '@voltaire/primitives/BlockHeader'
const header = BlockHeader.from({
parentHash: "0x...",
ommersHash: "0x...",
beneficiary: "0x...",
stateRoot: "0x...",
transactionsRoot: "0x...",
receiptsRoot: "0x...",
logsBloom: new Uint8Array(256),
difficulty: 0n,
number: 18000000n,
gasLimit: 30000000n,
gasUsed: 15000000n,
timestamp: 1700000000n,
extraData: new Uint8Array(0),
mixHash: "0x...",
nonce: new Uint8Array(8),
baseFeePerGas: 30000000000n,
})
Type Definition
type BlockHeaderType = {
readonly parentHash: BlockHashType
readonly ommersHash: HashType
readonly beneficiary: AddressType
readonly stateRoot: HashType
readonly transactionsRoot: HashType
readonly receiptsRoot: HashType
readonly logsBloom: Uint8Array // 256 bytes
readonly difficulty: Uint256Type
readonly number: BlockNumberType
readonly gasLimit: Uint256Type
readonly gasUsed: Uint256Type
readonly timestamp: Uint256Type
readonly extraData: Uint8Array // max 32 bytes
readonly mixHash: HashType
readonly nonce: Uint8Array // 8 bytes
readonly baseFeePerGas?: Uint256Type // EIP-1559 (London)
readonly withdrawalsRoot?: HashType // Shanghai
readonly blobGasUsed?: Uint256Type // EIP-4844 (Cancun)
readonly excessBlobGas?: Uint256Type // EIP-4844 (Cancun)
readonly parentBeaconBlockRoot?: HashType // EIP-4788 (Cancun)
}
from
Universal constructor with all header fields.
const header = BlockHeader.from({
// Required fields (all blocks)
parentHash: "0x1234...",
ommersHash: "0x1dcc...", // Usually empty hash post-merge
beneficiary: "0xfee...", // Fee recipient
stateRoot: "0xabcd...",
transactionsRoot: "0xef01...",
receiptsRoot: "0x2345...",
logsBloom: new Uint8Array(256),
difficulty: 0n, // 0 post-merge
number: 18500000n,
gasLimit: 30000000n,
gasUsed: 12345678n,
timestamp: 1700000000n,
extraData: new Uint8Array(0),
mixHash: "0x0000...", // 0 post-merge
nonce: new Uint8Array(8), // 0 post-merge
// EIP-1559 (London fork)
baseFeePerGas: 30000000000n,
// Shanghai fork
withdrawalsRoot: "0x5678...",
// EIP-4844 (Cancun fork)
blobGasUsed: 262144n,
excessBlobGas: 0n,
parentBeaconBlockRoot: "0x9abc...",
})
Genesis (All Blocks)
| Field | Description |
|---|
| parentHash | Hash of parent block |
| ommersHash | Hash of ommers list RLP |
| beneficiary | Block reward recipient |
| stateRoot | State trie root after execution |
| transactionsRoot | Transactions trie root |
| receiptsRoot | Receipts trie root |
| logsBloom | 256-byte bloom filter for logs |
| difficulty | PoW difficulty (0 post-merge) |
| number | Block height |
| gasLimit | Max gas for block |
| gasUsed | Total gas consumed |
| timestamp | Unix timestamp (seconds) |
| extraData | Arbitrary data (max 32 bytes) |
| mixHash | PoW mix hash (0 post-merge) |
| nonce | PoW nonce (0 post-merge) |
EIP-1559 (London Fork)
| Field | Description |
|---|
| baseFeePerGas | Dynamic base fee per gas |
Shanghai Fork
| Field | Description |
|---|
| withdrawalsRoot | Merkle root of withdrawals |
EIP-4844 (Cancun Fork)
| Field | Description |
|---|
| blobGasUsed | Total blob gas used |
| excessBlobGas | Excess blob gas for pricing |
| parentBeaconBlockRoot | Beacon chain parent root |
Post-Merge Changes
After The Merge, several fields are deprecated but still present:
const postMergeHeader = BlockHeader.from({
// ...other fields
difficulty: 0n, // Always 0
mixHash: "0x" + "00".repeat(32), // RANDAO reveal
nonce: new Uint8Array(8), // Always 0
})
See Also
