guess.js

web3.eth.getBlock('latest', function(e, r) {
  var data = {number: r.number, hash: r.hash, timestamp: r.timestamp };
  var sha3 = web3.sha3([data.hash.slice(2), (data.timestamp + 14).toString(16).padStart(64, "0")].join(''), {encoding: 'hex'});
  data.answer = parseInt(sha3.slice(-2), 16);
  contractInstance.guess(data.answer, {value: 1000000000000000000}, function(x, v) { })
});