Simple Blockchain made with JS

mitracoin.js

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

class Block {
	constructor(index, timestamp, data, previousHash = ''){
		this.index = index;
		this.timestamp = timestamp;
		this.data = data;
		this.previousHash = previousHash;
		this.hash = this.calculateHash();
		this.nonce = 0;
	}

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

	// We need to make the stat of the hash begin with a certian amount of zeroes
	mineBlock(difficulty) {
		while(this.hash.substring(0, difficulty) !== Array(difficulty+1).join("0")){
			this.nonce++;
			this.hash = this.calculateHash();
		}
		console.log("Block mined:" + this.hash)
	}
}

class Blockchain {
	constructor(){
		this.difficulty = 3;
		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.mineBlock(this.difficulty)
		newBlock.hash = newBlock.calculateHash();
		this.chain.push(newBlock);
	}
}

let mitraCoin = new Blockchain();
mitraCoin.createGenesisBlock()
mitraCoin.addBlock(new Block(1, '10/07/2017', { amount: 5}))
mitraCoin.addBlock(new Block(2, '10/07/2017', { amount: 3}))
console.log(JSON.stringify(mitraCoin, null, 4))