Unlock the Power of Blockchain Development

With the average blockchain developer salary reaching $154,550/year, now is an excellent time to dive into this exciting field. And the best part? You don’t need to be a cryptography expert to get started. If you have a basic understanding of JavaScript, you’re ready to begin.

Understanding the Basics

Before we dive into the world of blockchain development, let’s define two essential terms: the blockchain and a bitcoin transaction. The blockchain is an immutable, distributed database that records a global log of transactions. A block in the blockchain is similar to a record in traditional databases. A bitcoin transaction, on the other hand, is the transfer of value from one bitcoin wallet to another that gets included in the blockchain.

Setting Up a Testnet Wallet

To get started, we need a Testnet wallet and some bitcoins to play with. You can generate a Testnet wallet using a website or bitcore-core. I’ve generated one for demonstration purposes:

Private key = 93F2mUJPKbXW8Q9cMNz4ZmpsjgTbNjrMeCaUesTPE7k1DFhSmnk
Address = mtVE8anM63kQcgKUC6oQQD9K6xiV4wsr7q

Let’s send some bitcoin to this address using a bitcoin Testnet faucet website. Now that we have some bitcoin in our wallet, we can create a simple Node.js application to send bitcoin.

Building a Node.js Application

We’ll use the Bitcore open-source library and Axios to interface with the blockchain. Create an index.js file and import the Bitcore and Axios libraries:

const bitcore = require('bitcore-lib');
const axios = require('axios');

Then, create a function sendBitcoin that will send the bitcoin:

async function sendBitcoin(receiverAddress, amount) {
  // implementation
}

Unspent Outputs and Transaction Fees

Unspent outputs are the transactions you received to your bitcoin wallet that have not been spent. To find out how many outputs we have in our wallet, we’ll use the SoChain block explorer.

We’ll then use this data to build new inputs and calculate the transaction fee.

Building New Inputs and Setting the Transaction Fee

From the unspent outputs, we’ll build a new input equal to the unspent outputs. We’ll grab the essential elements of the outputs we need to create new inputs from the unspent output array. Then, we’ll set the transaction inputs and deal with the bitcoin transaction fees.

const unspentOutputs = [...]; // get unspent outputs from SoChain
const newInputs = unspentOutputs.map((output) => {
  // create new input from output
});

const transactionFee = calculateTransactionFee(newInputs);

Setting the Bitcoin Receiver Address, Amount to Send, and Fees

Now that we’ve calculated the fees and verified that we have enough balance to cover the transaction, we can set the receiving address and fees with the Bitcore API:

const transaction = new bitcore.Transaction();
transaction.to(receiverAddress, amount);
transaction.fee(transactionFee);

Setting Up the Bitcoin Change Address

We’ll use the Bitcore function transaction.change to set the change address, which is our address – the address we want to receive the balance paid into after sending to the receiver.

transaction.change(ourAddress);

Signing and Serializing the Transaction

Before we can spend bitcoin in a wallet, we must have the private key of that wallet. We’ll sign the transaction using the private key and serialize the transaction to get the transaction hex:

const privateKey = new bitcore.PrivateKey(privateKeyHex);
const signedTransaction = transaction.sign(privateKey);
const transactionHex = signedTransaction.serialize();

Broadcasting the Bitcoin Transaction

Finally, we’ll broadcast the transaction to the blockchain through the SoChain node with a post request to the API:

axios.post('https://sochain.com/api/v2/send_tx/BTC', {
  tx_hex: transactionHex,
}).then((response) => {
  console.log(response.data);
}).catch((error) => {
  console.error(error);
});

Congratulations! You’ve successfully sent bitcoin.

What’s Next?

There’s a lot more to learn about the blockchain, cryptocurrencies, and how to work with them. This tutorial should provide you with basic information on how to use JavaScript to send bitcoin from your wallet. From here, you can build upon your knowledge and explore more advanced topics.

Happy Hacking!