Assignment 15

by MimiE

HTML

<br><br>
		Input a Number:
		<input id="text"><br><br>
		<button onclick="add()" id="output0">Add Blockchain</button>
		<button onclick="invalidate()" id="output1">Invalidate Blockchain</button><br><br>
		<div id="value"><hr></div>
		<br>

JavaScript

// linked list
var Node = function(a) {
  this.next = null;
  this.prev = null;
  this.key = a;
  return this;
}

var List = function(a) {
  this.head = null;
  this.tail = null;
  this.length = 0;
  return this;
}

// converts list to string
List.prototype.listToString = function() {
  var str = ''; //insert string here
  var anode = this.head;
  while (anode != null) {
    str += anode.key + '<br>';
    anode = anode.next;
  }
  return str;
}

List.prototype.push = function(a) {
  var node = new Node(a);
  // node.c = a;
  if (this.head == null) {
    this.head = node;
    this.tail = node;
    this.length++;
    return node;
  }

  node.prev = this.tail;
  this.tail.next = node;
  this.tail = node;
  this.length++;
  return node;
}

List.prototype.pop = function() {
  var poppedNode = this.tail;
  if (this.head == null) {
    alert(''); //alerts.
    return null;
  }
  if (this.head == this.tail) {
    this.head = null;
    this.tail = null;
    this.length--;
    return poppedNode;
  }
  this.tail = this.tail.prev;
  this.tail.next = null;
  this.length--;
  return poppedNode;
}

List.prototype.peek = function(){
    return this.tail;
}

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

  calculateHash(){
    return SHA1(this.previousHash + JSON.stringify(this.data)).toString();
  }
}

class Blockchain {
  constructor() {
      this.chain = new List();
        this.createGenesisBlock();
  }

  createGenesisBlock(){
    const block = new Block("Genesis Block", "0");
        block.hash = block.calculateHash();
        this.chain.push(block);
  }

  getLatestBlock() {
    return this.chain.peek();
  }

  addBlock(amt) {
        const block = new Block(amt);
    block.previousHash = this.getLatestBlock().key.hash;
    block.hash = block.calculateHash();
    this.chain.push(block);

        var outputArea = document.getElementById('value');
        outputArea.innerHTML +=...