intro.js

const lightningHash = (data) => {
  return data + '*';
};

class Block {
  constructor(data, hash, lastHash) {
    this.data = data;
    this.hash = hash;
    this.lastHash = lastHash;
  }
}

class Blockchain {
  constructor() {
    const genesis = new Block('gen-data', 'gen-hash', 'gen-lastHash');

    this.chain = [genesis];
  }

  addBlock(data) {
    const lastHash = this.chain[this.chain.length - 1].hash;

    const hash = lightningHash(data + lastHash);

    const block = new Block(data, hash, lastHash);

    this.chain.push(block);
  }
}

const fooBlockchain = new Blockchain();

fooBlockchain.addBlock('one');
fooBlockchain.addBlock('two');
fooBlockchain.addBlock('three');

console.log(fooBlockchain);