Learn Blockchain Programming with JavaScript

By : Traub

3 (5)

Buy this Book

Learn Blockchain Programming with JavaScript

3 (5)

By: Traub

Buy this Book

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

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Free Chapter

Setting up the Project

What is a blockchain?

What you will learn...

Environment setup

Summary

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

Summary

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

Summary

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

Summary

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

Summary

Consensus Algorithms

What is the consensus algorithm ?

Building the chainIsValid method

Building the /consensus endpoint

Summary

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

Summary

In conclusion...

A quick review

Areas of improvement

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Testing the new and updated /mine endpoints

Let's test the updated /mine endpoint and the /receive-new-block endpoint that we just created. Basically, the /mine endpoint will mine the new block for us. It will also take that block and broadcast it across the entire blockchain network so that every node is synchronized and all the nodes have the same blocks and the same data. This is the result we expect to observe when we test the /mine endpoint:

To get started, you should have all five of the nodes running. You should also have connected them together to create a blockchain network.
Next, go to the browser. The first thing to do here is to choose a node to mine the new block. We have got five nodes to choose from but in our case, we will just stick with the first node. Therefore, type localhost:3001/mine in the address bar and then hit Enter. You will get an output like...