send tx bitcoin

sendtxbitcoin.js

var bitcoin = require("bitcoinjs-lib");
var axios = require("axios");

const TestNet = bitcoin.networks.testnet;

// https://testnet.manu.backend.hamburg/faucet
// https://testnet.coinfaucet.eu/en/
// https://testnet.blockexplorer.com/address/n2AxiA2Fd7y4spAciPXKUxKFpEPezpyRzR

const run = async () => {
    // generate
    // var keyPair = bitcoin.ECPair.makeRandom({ network: TestNet });
    // console.log('levy2', keyPair.getAddress());
    // console.log('levy3', keyPair.toWIF());

    // From n2AxiA2Fd7y4spAciPXKUxKFpEPezpyRzR
    var keyPair1 = bitcoin.ECPair.fromWIF('cW4r4rajDoKwpEgRPkyF7w7HLaZ7R9zBEDwHtVf2RR1EyBCggESB', TestNet);
    console.log('levy4', keyPair1.getAddress());
    console.log('levy5', keyPair1.toWIF());

    // To mz5HhsVBJsY7BFSvbtDefvdvaNzTvmsawp
    var keyPair2 = bitcoin.ECPair.fromWIF('cNurxkqx9zifbnVR7HgPGwSjDcZVhYeUCTzpwBHKhjCq6TbT4RML', TestNet);
    console.log('levy4', keyPair2.getAddress());
    console.log('levy5', keyPair2.toWIF());

    // https://blockchain.info/unspent?address=
    let apiUrl = 'https://testnet.blockexplorer.com/api/addr/'

    // log unspent transactions
    const utxo = await axios.get(apiUrl + keyPair1.getAddress() + '/utxo');
    console.log(utxo.data);

    // log balance
    const balance = await axios.get(apiUrl + keyPair1.getAddress() + '/balance');
    console.log(balance.data);

    // Transaction
    let tx = new bitcoin.TransactionBuilder(TestNet);
    let amountWeHave = balance.data // 1.1 BTC
    let amountToKeep = balance.data - 100000000 //200000000 // 1 BTC
    let transactionFee = 1000 // .00001 BTC
    let amountToSend = amountWeHave - amountToKeep - transactionFee

    tx.addInput(utxo.data[utxo.data.length - 1].txid, 0);
    tx.addOutput(keyPair2.getAddress(), amountToSend);
    tx.addOutput(keyPair1.getAddress(), amountToKeep);
    tx.sign(0, keyPair1); // 0 refers to the first input
    let tx_hex = tx.build().toHex();

    var txDecoded = bitcoin.Transaction.fromHex(tx_hex);
    var txid = txDecoded.getId();
    console.log(`********* TX - ${txid} **********`);
    console.log(tx_hex);
    console.log('*******************');
}

run();