The book assumes that you are comfortable using a command-line interface, though doesn't require any formal shell scripting skills. Basic language-agnostic programming knowledge is also assumed, and, in some cases, a familiarity with a particular language would be beneficial, though isn't a requirement.

As the book covers many languages and technologies, it is unlikely the reader will be familiar with all of them. As such, a willingness to learn is certainly recommended.

You can download the example code files for this book from your account at www.packt.com. If you purchased this book elsewhere, you can visit www.packt.com/support and register to have the files emailed directly to you.

You can download the code files by following these steps:

1. Log in or register at www.packt.com.
2. Select the SUPPORT tab.
3. Click on Code Downloads & Errata.
4. Enter the name of the book in the Search box and follow the onscreen instructions.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

• WinRAR/7-Zip for Windows
• Zipeg/iZip/UnRarX for Mac
• 7-Zip/PeaZip for Linux

The code bundle for the book is also hosted on GitHub at https://github.com/PacktPublishing/Blockchain-By-Example. In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

We also provide a PDF file that has color images of the screenshots/diagrams used in this book. You can download it here: https://www.packtpub.com/sites/default/files/downloads/9781788475686_ColorImages.pdf.

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "You can, at any level, use console.log() to print the received values in the console."

A block of code is set as follows:

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

Any command-line input or output is written as follows:

sudo add-apt-repository ppa:bitcoin/bitcoin 
sudo apt-get update

Bold: Indicates a new term, an important word, or words that you see on screen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "The customer can check the transaction details before proceeding with the payment by pressing the Transaction details button."