@stellarshift/abi-tools

Compute function selectors and event topic0 hashes from canonical Solidity ABI type strings.

Handy for calldata decoders, integration tests, and interview exercises that ask candidates to match on-chain logs without importing full ethers ABI codecs.

Install

npm install @stellarshift/abi-tools

Usage

const {
  getFunctionSelector,
  getEventTopic0,
  buildFunctionSignature,
  selectorFromSignature,
} = require('@stellarshift/abi-tools');

getFunctionSelector('transfer', ['address', 'uint256']);
// → '0xa9059cbb'

buildFunctionSignature('approve', ['address', 'uint256']);
// → 'approve(address,uint256)'

selectorFromSignature('balanceOf(address)');
// → '0x70a08231'

getEventTopic0('Transfer', ['address', 'address', 'uint256']);
// → '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef'

API

| Function | Returns | |----------|---------| | getFunctionSelector(name, types[]) | 4-byte 0x selector | | getEventTopic0(name, types[]) | 32-byte topic hash | | buildFunctionSignature(name, types[]) | Canonical string | | selectorFromSignature(sig) | Selector from full signature | | normalizeType(type) | uint → uint256, etc. | | isSelector(hex) | Validates 0x + 8 hex |

Implementation

Uses js-sha3 for Keccak-256 (Ethereum variant).

Does not ABI-encode arguments — selectors / topics only.

License

MIT © StellarShift Labs