savjee Blockchain javascript tutorial

main.js

/**
 * Description: My Blockchain tut- savjee Blockchain javascript tutorial, https://github.com/SavjeeTutorials/SavjeeCoin/blob/master/src/main.js,https://www.youtube.com/watch?v=zVqczFZr124
 * Version: 1.0
 * Author: Mark Lovett
 * Author URI: https://marklovettdesign.com
 */


const SHA256 = require("crypto-js/sha256");

class Block {
    constructor(index, timestamp, data, previousHash = '') {
        this.index = index;
        this.previousHash = previousHash;
        this.timestamp = timestamp;
        this.data = data;
        this.hash = this.calculateHash();
    }

    calculateHash() {
      return SHA256(this.index + this.previousHash + this.timestamp + JSON.stringify(this.data)).toString();
    }
}


class Blockchain {
    constructor() {
        this.chain = [this.createGenesisBlock()];
    }

    createGenesisBlock() {
        return new Block(0, "01/01/2017", "Genesis block", "0");
    }

    getLatestBlock() {
        return this.chain[this.chain.length - 1];
    }

    addBlock(newBlock) {
        newBlock.previousHash = this.getLatestBlock().hash;
        newBlock.hash = newBlock.calculateHash();
        this.chain.push(newBlock);
    }
/*
    isChainValid() {
        for (let i = 1; i < this.chain.length; i++){
            const currentBlock = this.chain[i];
            const previousBlock = this.chain[i - 1];

            if (currentBlock.hash !== currentBlock.calculateHash()) {
                return false;
            }

            if (currentBlock.previousHash !== previousBlock.hash) {
                return false;
            }
        }

        return true;
    }
}
*/
let savjeeCoin = new Blockchain();
savjeeCoin.addBlock(new Block(1, "20/07/2017", { amount: 4 }));
savjeeCoin.addBlock(new Block(2, "20/07/2017", { amount: 8 }));


console.log('Blockchain valid? ' + savjeeCoin.isChainValid());
/*
console.log('Changing a block...');
savjeeCoin.chain[1].data = { amount: 100 };
// savjeeCoin.chain[1].hash = savjeeCoin.chain[1].calculateHash();

console.log("Blockchain valid? " + savjeeCoin.isChainValid());

// console.log(JSON.stringify(savjeeCoin, null, 4));
*/

my-blockchain.php

<?php
/**
 * Plugin Name: My Blockchain
 * Plugin URI: https://marklovettdesign.com
 * Description: savjee Blockchain javascript tutorial, https://github.com/SavjeeTutorials/SavjeeCoin/blob/master/src/main.js,https://www.youtube.com/watch?v=zVqczFZr124
 * Version: 1.0
 * Author: Mark Lovett
 * Author URI: https://marklovettdesign.com
 */

define( 'MY_BLOCKCHAIN_DIR', plugin_dir_path( __FILE__ ) );
define( 'MY_BLOCKCHAIN_URL', plugins_url( '/', __FILE__ ) );

require 'js/main.js';