Fummpel NPM | npm.io

Usage

API

TokenIDs

Main class representing a set of token IDs as BigInts. Construct either with a list / set of BigInts or decode from compressed bytes.

Generate Merkle tree roots / multi-proofs with root() and proof(...) and retrieve a compact binary representation with 'encode()`

`new TokenIDs(tokenIDs: Iterable<bigint>)`

Create a new list of tokens from any Iterable, e.g. Set / Array. Token IDs must be 256-bit BigInts

`TokenIDs.decode(bytes: Uint8Array): TokenIDs`

Decode tokens from a compressed byte stream.

`encode()`

Gets compressed binary representation of all token IDs

`proof(subset: Iterable<bigint>)`

Generates Merkle multi-proof for subset of token IDs

`root()`

Gets Merkle tree root hash

`tokens()`

Gets list of token IDs represented by this TokenIDs instance as a sorted array

`verify(proof: string[], flags: boolean[], leaves: string[][]): boolean`

Verify multiproof using essentially the same algo in OpenZeppelin's smart contract

Example

import { TokenIDs } from 'fummpel';

// keccak256 needs to be initialized
await TokenIDs.init();

const tokens = new TokenIDs([2n,3n,5n,7n])

// Merkle root for these 4 tokens
const root = tokens.root();
// '0xc97e9e1eb896293c19f2649c796c9a276d997cfa58164c5f25d9a3f29b894cc9'

// Merkle multiproof for 2 of the tokens
const proof = tokens.proof([2n, 5n]);
// {
//   leaves: [ 5n, 2n ],
//   proof: [
//     '0xcff8e1781584200105067c0684580a1524c9539de52c1f9889e2cf73830cfccc'
//   ],
//   proofFlags: [ true, false ]
// }

// Leaf error if token is not in tree
const bad = tokens.proof([1n]);
// Error: Leaf is not in tree

// Verify multiproof
const verified = tokens.verify(proof.proof, proof.proofFlags, proof.leaves);
// true

// Get encoded tokens list
const encoded = tokens.encoded();
// Uint8Array(2) [ ... ]

// Decode encoded tokens list
const decoded_tokens = TokenIDs.decode(encoded);
// TokenIDs { ... }

const decoded_token_ids = decoded_tokens.tokens();
// [ 2n, 3n, 5n, 7n ]