BlockChain from Scratch Part 01 - javascript

BlockChain1.js

var crypto = require('crypto')
  , shasum = crypto.createHash('sha1');
/*
 * Install "cyrpto" lib dependeny to compute the hash
 *  `npm install crypto`
 */

class TRBlock {
  /**
   * constructor for creating a block
   * @param {Number} index - the index of the Block
   * @param {Number} timestamp - epoch time, secs from Jan 1 1972
   * @param {Object} data - the data to be stored on block chain
   * @param {String} prevHash - hash of the previous block
   * @param {String} nonce - the string to be mined
   * @param {Number} target - the Number of leading zeros to mine nonce
   */
  constructor(index, timestamp, data, prevHash, nonce, target){
    this.index = index;
    this.timestamp = timestamp;
    this.data = data;
    this.prevHash = prevHash;
    this.nonce = nonce;
    this.target = target;
  }
  
  /**
   * Compute sha-1 hash and return hexadeicmal hash
   * @return SHA-1 hexadeicmal hash
   */
  computeHash(){
    shasum.update(JSON.stringify(this));
    return shasum.digest("hex");
  }
}

var block = new TRBlock(0, 1514528022, "Hello World",
                "000000000000000000000000000", "Random nonce", 8);
console.log(block.computeHash());