a simple plain JS konami code listener

konami.js

// https://en.wikipedia.org/wiki/Konami_Code
// up, up, down, down, left, right, left, right, b, a, esc (in the real world was "start")
let konami_code = [38, 38, 40, 40, 37, 39, 37, 39, 66, 65, 27];
let pressed = [];

document.addEventListener("keydown", event => {
  // 229 is the key code android devices send when their software keyboards are guesing key presses
  // https://bugs.chromium.org/p/chromium/issues/detail?id=118639
  if (event.isComposing || event.keyCode === 229) {
    return;
  }
  // check the code
  pressed.push(event.which);
  if (pressed.length > konami_code.length) {
    pressed.shift();
  }
  is_secret = (konami_code.length == pressed.length) &&
  	konami_code.reduce((accum, val, i, s) => {
  		return accum && (val == pressed[i]);
      }, true);
  if (is_secret) {
    console.log('you pressed the secret code');
  }
});