Prog. 1: Blockchain’s Block creation using JavaScript

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();

}

calculateHash()

{

return SHA256(this.index+this.timestamp+this.previoushash+JSON.stringify(this.data)).toString();

}

} //close block class class Blockchain

{

constructor(index,timestamp,data,previoushash=‘‘)

{

this.index = index; 
this.timestamp = timestamp; 
this.data = data; 
this.previoushash = previoushash;

this.chain =[this.createGenesisBlock()];

}

createGenesisBlock()

{

return new Block(0,”23/11/2021”,”This is First Program of Blockchain creation”,”0”);

}

addBlock(newBlock)

{

newBlock.previoushash = this.getLatestBlock().hash; 
newBlock.hash = newBlock.calculateHash(); 
this.chain.push(newBlock);

}

getLatestBlock()

{

return this.chain[this.chain.length-1];

}

} // close blockchain class

let block1 = new Block(1,”22/11/2021”,”Data1”,”0”);

let block2 = new Block(2,”21/11/2021”,”Second Block”,”“); 
let block3 = new Block(3,”14/05/2021”,”Third Block”,”“);

let myBlockchain = new Blockchain(); myBlockchain.addBlock(block1); 
myBlockchain.addBlock(block2); myBlockchain.addBlock(block3); 
console.log(JSON.stringify(myBlockchain,null,4));

output: