viem
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JavaScript
import { estimateGas, } from '../../actions/public/estimateGas.js';
import { readContract, } from '../../actions/public/readContract.js';
import { getChainContractAddress } from '../../utils/chain/getChainContractAddress.js';
import { l1BlockAbi } from '../abis.js';
import { contracts } from '../contracts.js';
/**
* Estimates the operator fee required to execute an L2 transaction.
*
* Operator fees are part of the Isthmus upgrade and allow OP Stack operators
* to recover costs related to Alt-DA, ZK proving, or custom gas tokens.
* Returns 0 for pre-Isthmus chains or when operator fee functions don't exist.
*
* @param client - Client to use
* @param parameters - {@link EstimateOperatorFeeParameters}
* @returns The operator fee (in wei). {@link EstimateOperatorFeeReturnType}
*
* @example
* import { createPublicClient, http, parseEther } from 'viem'
* import { optimism } from 'viem/chains'
* import { estimateOperatorFee } from 'viem/chains/optimism'
*
* const client = createPublicClient({
* chain: optimism,
* transport: http(),
* })
* const operatorFee = await estimateOperatorFee(client, {
* account: '0xA0Cf798816D4b9b9866b5330EEa46a18382f251e',
* to: '0x70997970c51812dc3a010c7d01b50e0d17dc79c8',
* value: parseEther('1'),
* })
*/
export async function estimateOperatorFee(client, args) {
const { chain = client.chain, l1BlockAddress: l1BlockAddress_ } = args;
const l1BlockAddress = (() => {
if (l1BlockAddress_)
return l1BlockAddress_;
if (chain?.contracts?.l1Block)
return getChainContractAddress({
chain,
contract: 'l1Block',
});
return contracts.l1Block.address;
})();
// Try to get operator fee parameters. If any of these calls fail,
// it means this is a pre-Isthmus chain and operator fees don't apply
try {
// Get operator fee parameters first to fail fast if not supported
const [operatorFeeScalar, operatorFeeConstant] = await Promise.all([
readContract(client, {
abi: l1BlockAbi,
address: l1BlockAddress,
functionName: 'operatorFeeScalar',
}),
readContract(client, {
abi: l1BlockAbi,
address: l1BlockAddress,
functionName: 'operatorFeeConstant',
}),
]);
// Estimate gas for the actual transaction
const gasUsed = await estimateGas(client, args);
// Calculate operator fee: saturatingAdd(saturatingMul(gasUsed, scalar) / 1e6, constant)
// Using saturating arithmetic to prevent overflow
const scaledFee = (gasUsed * BigInt(operatorFeeScalar)) / 1000000n;
return scaledFee + BigInt(operatorFeeConstant);
}
catch {
// If any call fails, this is likely a pre-Isthmus chain or the contract
// doesn't support these functions. Return 0 for operator fee.
return 0n;
}
}
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