Initial blockchain commit

block.ts

@@ -0,0 +1,39 @@
+const sha256 = require('sha256')
+
+type Data = any
+
+type BlockArguments = {
+  id: number,
+  timestamp: number,
+  data: any,
+  nonce: string
+  previousHash: string
+}
+
+export default class Block {
+  public index = 0
+  public timestamp: number
+  public data: any
+  public previousHash: string
+  public hash: string
+  public nonce: string
+
+  constructor (args: BlockArguments) {
+    this.index = args.id
+    this.timestamp = args.timestamp
+    this.data = args.data
+    this.nonce = args.nonce
+    this.previousHash = args.previousHash
+
+    this.hash = this.calculateHash()
+  }
+
+  calculateHash (): string {
+    const toBeHashed = this.previousHash + (this.index + this.timestamp + this.data + this.nonce)
+
+    return sha256(toBeHashed)
+  }
+
+  mineBlock (difficulty) {
+  }
+}

blockchain.ts

@@ -0,0 +1,51 @@
+import Block from './block'
+
+export default class Blockchain {
+  private chain: Block[] = []
+  constructor() {
+    this.chain.push(this.createGenesisBlock())
+  }
+
+  public createGenesisBlock(): Block {
+    return new Block({
+      id: 0,
+      timestamp: Date.now(),
+      data: "Initial Block",
+      previousHash: "",
+      nonce: "0"
+    })
+  }
+
+  public getLatestBlock (): Block {
+    return this.chain[this.getChainLength() - 1]
+  }
+
+  public getChainLength(): number {
+    return this.chain.length
+  }
+
+  public addBlock (data): void {
+    const block = new Block({
+      id: this.getChainLength(),
+      timestamp: Date.now(),
+      data: data,
+      previousHash: this.getLatestBlock().hash,
+      nonce: "0"
+    })
+
+    this.chain.push(block)
+  }
+
+  public checkValid (): boolean {
+    for (let i = this.getChainLength() - 1; i > 0; --i) {
+      const currentBlock = this.chain[i]
+      const previousBlock = this.chain[i - 1]
+
+      if (currentBlock.previousHash != previousBlock.hash) {
+        return false
+      }
+    }
+
+    return true
+  }
+}

index.ts

@@ -0,0 +1,9 @@
+import Blockchain from './blockchain'
+import Block from './block'
+
+let chain = new Blockchain();
+chain.addBlock({amount: 5})
+chain.addBlock({amount: 10})
+
+console.log(JSON.stringify(chain, null, 4))
+console.log("Is blockchain valid? " + chain.checkValid())

package.json

@@ -0,0 +1,16 @@
+{
+  "name": "blockchain",
+  "version": "1.0.0",
+  "description": "",
+  "main": "block.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "@types/node": "^10.12.12",
+    "sha256": "^0.2.0",
+    "sjcl": "^1.0.8"
+  }
+}