bitcoind.md

Bitcoin Service

The Bitcoin Service adds a native Node.js interface to Bitcoin Core for querying information about the Bitcoin blockchain. Bindings are linked to Bitcoin Core compiled as a static library.

API Documentation

These methods are currently only available via directly interfacing with a node:

node.services.bitcoind.<methodName>

Getting Block Information

It's possible to query blocks by both block hash and by height. Blocks are given as Node.js buffers and can be parsed via Bitcore:

var blockHeight = 0;
node.services.bitcoind.getBlock(blockHeight, function(err, blockBuffer) {
  if (err) {
    throw err;
  }
  var block = bitcore.Block.fromBuffer(blockBuffer);
  console.log(block);
};

// check if the block is part of the main chain
var mainChain = node.services.bitcoind.isMainChain(block.hash);
console.log(mainChain);

// get only the block index (including chain work and previous hash)
var blockIndex = node.services.bitcoind.getBlockIndex(blockHeight);
console.log(blockIndex);

Retrieving and Sending Transactions

Get a transaction asynchronously by reading it from disk, with an argument to optionally not include the mempool:

var txid = '7426c707d0e9705bdd8158e60983e37d0f5d63529086d6672b07d9238d5aa623';
var queryMempool = true;
node.services.bitcoind.getTransaction(txid, queryMempool, function(err, transactionBuffer) {
  if (err) {
    throw err;
  }
  var transaction = bitcore.Transaction().fromBuffer(transactionBuffer);
});


// also retrieve the block timestamp and height
node.services.bitcoind.getTransactionWithBlockInfo(txid, queryMempool, function(err, info) {
  console.log(info.blockHash);
  console.log(info.height);
  console.log(info.timestamp); // in seconds
  var transaction = bitcore.Transaction().fromBuffer(transactionBuffer);
});

Send a transaction to the network:

var numberOfBlocks = 3;
var feesPerKilobyte = node.services.bitcoind.estimateFee(numberOfBlocks); // in satoshis

try {
  node.services.bitcoind.sendTransaction(transaction.serialize());
} catch(err) {
  // handle error
}

Get all of the transactions in the mempool:

var mempool = node.services.bitcoind.getMempoolTransactions();
var transactions = [];
for (var i = 0; i < mempool.length; i++) {
  transactions.push(bitcore.Transaction().fromBuffer(transactions[i]));
}

Determine if an output is spent (excluding the mempool):

var spent = node.services.bitcoind.isSpent(txid, outputIndex);
console.log(spent);

Miscellaneous

• bitcoind.start(callback) - Start the JavaScript Bitcoin node, the callback is called when the daemon is ready.
• bitcoind.getInfo() - Basic information about the chain including total number of blocks.
• bitcoind.isSynced() - Returns a boolean if the daemon is fully synced (not the initial block download)
• bitcoind.syncPercentage() - Returns the current estimate of blockchain download as a percentage.
• bitcoind.stop(callback) - Stop the JavaScript bitcoin node safely, the callback will be called when bitcoind is closed. This will also be done automatically on process.exit. It also takes the bitcoind node off the libuv event loop. If the daemon object is the only thing on the event loop. Node will simply close.

Events

The Bitcoin Service doesn't expose any events via the Bus, however there are a few events that can be directly registered:

node.services.bitcoind.on('tip', function(blockHash) {
  // a new block tip has been added
});

node.services.bitcoind.on('tx', function(txInfo) {
  // a new transaction has entered the mempool
});

node.services.bitcoind.on('txleave', function(txLeaveInfo) {
  // a new transaction has left the mempool
});

The txInfo object will have the format:

{
  buffer: <Buffer...>,
  mempool: true, // will currently always be true
  hash: '7426c707d0e9705bdd8158e60983e37d0f5d63529086d6672b07d9238d5aa623'
}

The txLeaveInfo object will have the format:

{
  buffer: <Buffer...>,
  hash: '7426c707d0e9705bdd8158e60983e37d0f5d63529086d6672b07d9238d5aa623'
}