Blockchain By Example

Let's code

Start by creating a hello.js file and importing the bitcoinjs-lib and request-promise modules using the require directive as follows:

var bitcoin = require('bitcoinjs-lib');var rp = require('request-promise');

Then we declare and define the necessary variables:

var data = Buffer.from('Hello World', 'utf8');var testnet = bitcoin.networks.testnet;var privateKey = 'cQx4Ucd3uXEpa3bNnS1JJ84gWn5djChfChtfHSkRaDNZQYA1FYnr';var SourceAddress = "n3CKupfRCJ6Bnmr78mw9eyeszUSkfyHcPy";

They represent respectively:

• The message to be embedded in the transaction
• The network—testnet
• The private key in WIF (short for Wallet Import Format)
• The source address from which we spend the UTXO

Then we ask the API to provide us with the available unspent ...