Overview
Gas provides branded types for gas limits and gas prices, preventing common bugs like mixing these values. Includes GasLimit for transaction gas limits and GasPrice for gas prices in wei.
import { GasLimit, GasPrice } from '@voltaire/primitives/Gas'
const limit = GasLimit.from(21000)
const price = GasPrice.fromGwei(20) // 20 gwei
const fee = GasLimit.toBigInt(21000) * GasPrice.toBigInt(price)
Type Definitions
type GasLimitType = bigint & { readonly [brand]: "GasLimit" }
type GasPriceType = bigint & { readonly [brand]: "GasPrice" }
GasLimit
Creating GasLimit
from
Create from number, bigint, or hex string.
const limit1 = GasLimit.from(21000)
const limit2 = GasLimit.from(21000n)
const limit3 = GasLimit.from("0x5208") // 21000 in hex
GasLimit Constants
Pre-defined gas limits for common operations:
import { SIMPLE_TRANSFER, ERC20_TRANSFER, DEFAULT_LIMIT } from '@voltaire/primitives/Gas'
SIMPLE_TRANSFER // 21000 - ETH transfer
ERC20_TRANSFER // 65000 - ERC-20 token transfer
DEFAULT_LIMIT // 30000000 - Block gas limit
GasLimit Methods
toBigInt
Convert to bigint.
const n = GasLimit.toBigInt(21000) // 21000n
toNumber
Convert to number.
const n = GasLimit.toNumber(21000) // 21000
GasPrice
Creating GasPrice
from
Create from wei value (number, bigint, or hex string).
const price1 = GasPrice.from(20_000_000_000) // 20 gwei in wei
const price2 = GasPrice.from(20_000_000_000n)
const price3 = GasPrice.from("0x4a817c800") // 20 gwei
fromGwei
Create from gwei (more convenient for typical gas prices).
const price = GasPrice.fromGwei(20)
// Equivalent to: GasPrice.from(20_000_000_000n)
GasPrice Methods
toBigInt
Convert to bigint (wei).
const wei = GasPrice.toBigInt(price) // 20000000000n
toGwei
Convert to gwei.
const gwei = GasPrice.toGwei(price) // 20n
Fee Calculation
Calculate transaction fees with type safety:
import { GasLimit, GasPrice } from '@voltaire/primitives/Gas'
// Simple transfer
const gasLimit = GasLimit.from(21000)
const gasPrice = GasPrice.fromGwei(30)
const fee = GasLimit.toBigInt(gasLimit) * GasPrice.toBigInt(gasPrice)
// fee = 21000n * 30_000_000_000n = 630_000_000_000_000n wei
// = 0.00063 ETH
// EIP-1559 transaction
const maxFeePerGas = GasPrice.fromGwei(50)
const maxPriorityFeePerGas = GasPrice.fromGwei(2)
const maxFee = GasLimit.toBigInt(gasLimit) * GasPrice.toBigInt(maxFeePerGas)
// maxFee = 21000n * 50_000_000_000n = 1_050_000_000_000_000n wei
Common Gas Limits
| Operation | Gas Limit |
|---|
| ETH Transfer | 21,000 |
| ERC-20 Transfer | ~65,000 |
| ERC-20 Approve | ~45,000 |
| Uniswap Swap | ~150,000 |
| NFT Mint | ~100,000 |
| Contract Deploy | Variable |
EIP-1559 Gas Model
Post-London fork, gas pricing uses:
// Legacy (pre-EIP-1559)
const legacyTx = {
gasLimit: GasLimit.from(21000),
gasPrice: GasPrice.fromGwei(30),
}
// EIP-1559
const eip1559Tx = {
gasLimit: GasLimit.from(21000),
maxFeePerGas: GasPrice.fromGwei(50),
maxPriorityFeePerGas: GasPrice.fromGwei(2),
}
Actual gas price in EIP-1559 is: min(maxFeePerGas, baseFee + maxPriorityFeePerGas)
Namespace Usage
import { GasLimit, GasPrice } from '@voltaire/primitives/Gas'
// Using namespace objects
const limit = GasLimit.from(21000)
const limitBigInt = GasLimit.toBigInt(21000)
const price = GasPrice.from(20_000_000_000n)
const priceGwei = GasPrice.fromGwei(20)
const priceBigInt = GasPrice.toBigInt(priceGwei)
See Also
