Book Image

Learn Blockchain Programming with JavaScript

By : Eric Traub

Book Image

Learn Blockchain Programming with JavaScript

By: Eric Traub

Overview of this book

Learn Blockchain Programming with JavaScript begins by giving you a clear understanding of what blockchain technology is. You’ll then set up an environment to build your very own blockchain and you’ll add various functionalities to it. By adding functionalities to your blockchain such as the ability to mine new blocks, create transactions, and secure your blockchain through a proof-of-work you’ll gain an in-depth understanding of how blockchain technology functions. As you make your way through the chapters, you’ll learn how to build an API server to interact with your blockchain and how to host your blockchain on a decentralized network. You’ll also build a consensus algorithm and use it to verify data and keep the entire blockchain network synchronized. In the concluding chapters, you’ll finish building your blockchain prototype and gain a thorough understanding of why blockchain technology is so secure and valuable. By the end of this book, you'll understand how decentralized blockchain networks function and why decentralization is such an important feature for securing a blockchain.

Preface

Who this book is for

What this book covers

To get the most out of this book

Free Chapter

Setting up the Project

Setting up the Project

What is a blockchain?

What you will learn...

Environment setup

Building a Blockchain

Building a Blockchain

Before we get building...

Blockchain constructor function

Building the createNewBlock method

Building the getLastBlock method

Creating the createNewTransaction method

Hashing the data

What is a Proof of Work?

Creating a genesis block

Accessing the Blockchain through an API

Accessing the Blockchain through an API

Setting up Express.js

Building the API foundation

Installing Postman and body-parser

Building the /blockchain endpoint

Building the /transaction endpoint

Building the /mine endpoint

Testing the endpoints

Creating a Decentralized Blockchain Network

Creating a Decentralized Blockchain Network

Creating multiple nodes

Adding the currentNodeUrl

New endpoints outline

Building the /register-and-broadcast-node endpoint

Building the /register-node endpoint

Building the /register-nodes-bulk endpoint

Testing all of the network endpoints

Synchronizing the Network

Synchronizing the Network

Understanding the need to synchronize the network

Refactoring the createNewTransaction method and the /transaction endpoint

Building the /transaction/broadcast endpoint

Refactoring the /transaction endpoint

Testing the transaction endpoints

Updating the mining information

Building the /receive-new-block endpoint

Testing the new and updated /mine endpoints

Consensus Algorithms

Consensus Algorithms

What is the consensus algorithm ?

Building the chainIsValid method

Building the /consensus endpoint

Block Explorer

What is a block explorer?

Defining the block explorer endpoints

Building the getBlock method

Building the /block/:blockHash endpoint

Defining the getTransaction method

Building the /transaction/:transactionId endpoint

Building the getAddressData method

Developing the /address/:address endpoint

Adding the block explorer file

Block explorer file explanation

Testing our block explorer

In conclusion...

In conclusion...

Areas of improvement

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Summary

All blockchains have a consensus algorithm, and in this chapter, we built our own consensus algorithm that implements the longest chain rule. We started by building the chainIsValid method. In this method, we simply iterated through every single block inside of the blockchain, and compared hashes on every block to make sure that they are correct. Then we moved on to test the method. In addition to this, we built the /consensus endpoint with the help of the chainIsValid method.

In the next chapter, we're going to build a block explorer that we'll be able to access on the browser. This block explorer will allow us to interact with the blockchain through a user interface.