konami.js

konami(function(){
  console.log('KONAMI!!!');
});

function konami(fn, match) {
  var konamiCode = '3838404037393739666513';
  var sequence = '';
  match = match || konamiCode;
  window.addEventListener('keyup', function(event){
    sequence += event.keyCode;
    if (match === sequence) {
      fn();
    }
    if (match.indexOf(sequence) === -1) {
      sequence = '';
    }
  }, false); 
}