Introduction

The Electrum Cash Protocol (@electrum-cash/protocol) provides fully typed functions and events for all Electrum Cash methods.

For complete information on all typings, arguments and options available, read to the documentation generated from the source code.

Usage

Installation

Installation is easy, just get the library from NPM:

npm install @electrum-cash/protocol

Setup

Before you can make requests you first need to set up and connect to a server.

// Import the electrum protocol library.
import { initializeElectrumClient } from '@electrum-cash/protocol';

// Initialize an electrum client with following the electrum protocol.
const electrumClient = await initializeElectrumClient('Electrum Protocol Test', 'bch.imaginary.cash');

Event handling

After you have initialized an electrum client and subscribe to new information, it will emit fully typed subscription events.

// Set up handler functions for electrum events.
electrumClient.on('blockchain.headers.subscribe', handleNewBlockchainHeaders);
electrumClient.on('blockchain.address.subscribe', handleAddressStatusUpdates);
electrumClient.on('blockchain.transaction.subscribe', handleTransactionStatusUpdates);
electrumClient.on('blockchain.transaction.dsproof.subscribe', handleTransactionDoublespendEvents);

// Subscribe to block headers.
await subscribeToBlockheaderUpdates(electrumClient);

// Subscribe to address status updates for a given address.
await subscribeToAddressUpdates(electrumClient, someAddress);

// Subscribe to transaction block inclusion updates for a given transaction.
await subscribeToTransactionUpdates(electrumClient, someTransactionHash);

// Subscribe to transaction doublespend updates for a given transaction.
await subscribeToDoublespendUpdates(electrumClient, someTransactionHash);

Requesting data

After you have initialized an electrum client you can request data with the following functions.

Address

// Import address related requests.
import { fetchHistory, fetchPendingTransactions, fetchBalance, fetchUnspentTransactionOutputs } from '@electrum-cash/protocol';

// Fetch transaction history for an address.
const currentAddressHistory = await fetchHistory(electrumClient, someAddress);
console.log('history', currentAddressHistory);

// Fetch pending transactions relating to an address.
const pendingTransactions = await fetchPendingTransactions(electrumClient, someAddress);
console.log('pending transactions', pendingTransactions);

// Fetch the current spendable balance of an addess.
const currentTrustedBalance = await fetchBalance(electrumClient, someAddress);
console.log('trusted balance', currentTrustedBalance);

// Fetch a list of unspent transaction outputs for an address.
const currentUnspentOutputs = await fetchUnspentTransactionOutputs(electrumClient, someAddress);
console.log('unspent outputs', currentUnspentOutputs);

Blockchain

// Import chain related requests.
import { fetchBlockHeaderFromBlockHeight, fetchBlockHeaders, fetchBlockHeaderWithProofFromBlockHeight, fetchCurrentChainTip } from '@electrum-cash/protocol';

// Fetch the block header of a given block height.
const checkpointBlockHeader = await fetchBlockHeaderFromBlockHeight(electrumClient, someBlockHeight);
console.log('header from height', checkpointBlockHeader);

// Fetch three block headers start at a specified height.
const blockHeaders = await fetchBlockHeaders(electrumClient, electrumCheckpoint.height, 3);
console.log('list of headers', blockHeaders);

// Fetch a block header and merkle proof of the blocks inclusion in the chain.
const checkpointBlockHeaderWithProof = await fetchBlockHeaderWithProofFromBlockHeight(electrumClient, electrumCheckpoint.height, someBlockHeight);
console.log('header with proof', checkpointBlockHeaderWithProof);

// Fetch the current block height, also called the chain tip.
const currentChainTip = await fetchCurrentChainTip(electrumClient);
console.log('current chaintip', currentChainTip);

Transaction

// Import transaction related requests.
import { broadcastTransaction, fetchDoublespendProof, fetchTransaction, fetchTransactionBlockHeight, fetchTransactionProof } from '@electrum-cash/protocol';

// Broadcast a transaction to the network.
const transactionHash = await broadcastTransaction(electrumClient, someTransactionHash);
console.log('txhash', transactionHash);

// Fetch double spend proofs related to a transaction, if they exist.
const doublespendProof = await fetchDoublespendProof(electrumClient, someTransactionHash);
console.log('dsproof', doublespendProof);

// Fetch a raw transaction.
const transactionHex = await fetchTransaction(electrumClient, someTransactionHash);
console.log('fetch transaction', transactionHex);

// Fetch the block height a given transaction was included in, if possible.
const transactionBlockHeight= await fetchTransactionBlockHeight(electrumClient, someTransactionHash);
console.log('fetch transaction height', transactionBlockHeight);

// Fetch a merkle proof that a transaction was included in a specific block.
const transactionProof = await fetchTransactionProof(electrumClient, someTransactionHash, 800649);
console.log('fetch transaction proof', transactionProof);

Support

If you find bugs or have problems using this library, you can file issues on the Gitlab.