Dynamic difficulty

[k7n2g]

Hi been trying to get Dynamic difficulty to work can you show update for this or please point me in the right direction, have added a timestamp and nonce value,
let nonce = 0;

do {
  nonce++;
  timestamp = Date.now().getTime();
  this.hash.substr(-DIFFICULTY) = Block.adjustDifficulty({ genesisBlock: parentBlock, timestamp });
   &&
    this.hash === this._calculateHash())

( In File NewBlockHeader.js )

great job on site and explainer any help appreciated many thanks