SimpleBlockchainGenesis.js

const sha256 = require('sha256');

class Block {
  constructor(index, timestamp, data, prevHash) {
    this.index = index;
    this.timestamp = timestamp;
    this.data = data;
    this.prevHash = prevHash;
    this.thisHash = sha256(
      this.index + this.timestamp + this.data + this.prevHash
    );
  }
}

const createGenesisBlock = () => new Block(0, Date.now(), 'Genesis Block', '0');