Simple Chain

Example of how to implement a blockchain

Getting Started

These instructions will get you a copy of the project up and running on your local machine for development and testing purposes.

Prerequisites

Installing Node and NPM is pretty straightforward using the installer package available from the Node.js.

Install

To install the project dependencies run the following command

$ npm install

Testing

Testing is very important

To test this code: 1: Open a command prompt or terminal shell after installing node.js. 2: Enter a node session, also known as a REPL (Read-Evaluate-Print-Loop).

node

3: Copy and paste your code into your node session 4: Instantiate blockchain with blockchain variable

let blockchain = new Blockchain();

5: Generate 10 blocks using a for loop

for (var i = 0; i <= 10; i++) {
  blockchain.addBlock(new Block("test data "+i));
}

6: Validate blockchain

blockchain.validateChain();

7: Induce errors by changing block data

let inducedErrorBlocks = [2,4,7];
for (var i = 0; i < inducedErrorBlocks.length; i++) {
  blockchain.chain[inducedErrorBlocks[i]].data='induced chain error';
}

8: Validate blockchain. The chain should now fail with blocks 2,4, and 7.

blockchain.validateChain();

Credit

• Udacity