import { Abi } from '@tevm/voltaire/Abi';
import { Hex } from '@tevm/voltaire/Hex';
import { Address } from '@tevm/voltaire/Address';
// ERC-20 transfer function ABI
const erc20Abi = Abi([
{
type: "function",
name: "transfer",
stateMutability: "nonpayable",
inputs: [
{ type: "address", name: "to" },
{ type: "uint256", name: "amount" }
],
outputs: [{ type: "bool", name: "" }]
}
]);
// Encode transfer(address,uint256) function call
const recipient = "0x742d35cc6634c0532925a3b844bc9e7595f251e3";
const amount = 1000000000000000000n; // 1 token (18 decimals)
const calldata = erc20Abi.encode("transfer", [recipient, amount]);
// Result: 0xa9059cbb... (4-byte selector + ABI-encoded params)
// The calldata can be used in a transaction
const tx = {
to: "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48", // USDC contract
data: Hex.fromBytes(calldata),
value: 0n
};
Decode Calldata
Verify the encoded calldata by decoding it back:// Decode the calldata to verify
const decoded = erc20Abi.decodeData(calldata);
// decoded.name = "transfer"
// decoded.params = ["0x742d35cc6634c0532925a3b844bc9e7595f251e3", 1000000000000000000n]
Function Selector
The first 4 bytes are the function selector:const transferFn = erc20Abi.getFunction("transfer");
const selector = Abi.Function.getSelector(transferFn);
// 0xa9059cbb = keccak256("transfer(address,uint256)")[0:4]
const signature = Abi.Function.getSignature(transferFn);
// "transfer(address,uint256)"
Full Transaction with Signing
import { Secp256k1 } from '@tevm/voltaire/Secp256k1';
import { Transaction } from '@tevm/voltaire/Transaction';
import { Keccak256 } from '@tevm/voltaire/Keccak256';
// Build unsigned EIP-1559 transaction
const unsignedTx = Transaction.fromEIP1559({
chainId: 1n,
nonce: 0n,
maxPriorityFeePerGas: 1000000000n,
maxFeePerGas: 50000000000n,
gasLimit: 100000n,
to: Address.from("0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"),
value: 0n,
data: calldata
});
// Sign the transaction
const privateKey = Hex.toBytes("0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80");
const serialized = Transaction.serialize(unsignedTx);
const hash = Keccak256(serialized);
const signature = Secp256k1.sign(hash, privateKey);
// Create signed transaction
const signedTx = Transaction.addSignature(unsignedTx, signature);
const rawTx = Transaction.serialize(signedTx);
// Ready to broadcast via eth_sendRawTransaction
This is a fully executable example. View the complete source with test assertions at
examples/contracts/erc20-transfer.ts.