var pattern = ['ArrowUp', 'ArrowUp', 'ArrowDown', 'ArrowDown', 'ArrowLeft', 'ArrowRight', 'ArrowLeft', 'ArrowRight', 'b', 'a'];
var current = 0;

var keyHandler = function (event) {

  // If the key isn't in the pattern, or isn't the current key in the pattern, reset
  if (pattern.indexOf(event.key) < 0 || event.key !== pattern[current]) {
    current = 0;
    return;
  }

  // Update how much of the pattern is complete
  current++;

  // If complete, alert and reset
  if (pattern.length === current) {
    current = 0;
    var confettiSettings = { target: 'confetti-holder' };
    var confetti = new ConfettiGenerator(confettiSettings);
    confetti.render();
  }

};

// Listen for keydown events
document.addEventListener('keydown', keyHandler, false);