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.
Table of Contents (10 chapters)

Building the getLastBlock method

Now, the next method that we are going to add to our Blockchain constructor function will be the getLastBlock. This method will simply return the last block in our blockchain to us. Follow the below mentioned steps to build the method:

  1. Go to our dev/blockchain.js file, and after our createNewBlock method, add the following:
Blockchain.prototype.getLastBlock = function () { 

}
  1. Inside of this getLastBlock method, we will type the following highlighted line of code:
Blockchain.prototype.getLastBlock = function () { 
return this.chain[this.chain.length - 1];

}

The [this.chain.length - 1]; in this preceding code defines the position of the block in the chain, which, in our case, is the previous block, therefore negated by 1. This method is simple and straightforward, and we'll use it in later chapters.

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