var bitcoin = require('bitcoinjs-lib');

// define bitcoin addrewss we want to transfer coins from
var key = bitcoin.ECPair.fromWIF("L1Kzcyy88LyckShYdvoLFg1FYpB5ce1JmTYtieHrhkN65GhVoq73");

var txb = new bitcoin.TransactionBuilder();
// (in)15000 - (out)12000 = (fee)3000, this is the miner fee

// Alice's previous transaction output, has 15000 satoshis
txb.addInput('61d520ccb74288c96bc1a2b20ea1c0d5a704776dd0164a396efec3ea7040349d', 0);
txb.addOutput('1cMh228HTCiwS8ZsaakH8A8wze1JR5ZsP', 12000);

txb.sign(0, key);

var client = new bitcoin.Client({
  host: 'localhost',
  port: 8332,
  user: 'user',
  pass: 'pass'
});