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main.js
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main.js
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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.previousHash + this.timestamp + JSON.stringify(this.data) + this.nonce).toString();
}
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);
}
} //End of Block
class Blockchain{
constructor(){
this.chain =[this.createGenesisBlock()];
this.difficulty = 2;
}
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);
this.chain.push(newBlock);
}
isChainVaild(){
for (let i = 1; i < this.chain.length; i++){
const currentBlock = this.chain[i];
const previousBlock = this.chain[i -1];
if(currentBlock.hash !== currentBlock.calculateHash()){
return false;
}
if(previousBlock.hash !== previousBlock.hash){
return false;
}
}
return true;
}//isChainVaild
}//Blockchain
//firstCoin example
let firstCoin = new Blockchain();
console.log("Mining block 1......");
firstCoin.addBlock(new Block(1, "17/11/2017", { amount : 4}));
console.log("Mining block 2......");
firstCoin.addBlock(new Block(1, "18/11/2017", { amount : 10}));