KonamiCodeMixin.js

function KonamiCodeMixin (callback) {
  const KEYS = ['ArrowUp', 'ArrowUp', 'ArrowDown', 'ArrowDown', 'ArrowLeft', 'ArrowRight', 'ArrowLeft', 'ArrowRight', 'KeyB', 'KeyA']
  let i = 0
 
	return {
  	mounted () {
      window.addEventListener('keyup', this.onKeyUp)
    },
    destroyed () {
      window.removeEventListener('keyup', this.onKeyUp)
    },
    methods: {
      onKeyUp ({ code }) {
        i = KEYS[i] === code ? i + 1 : 0
        if (i !== KEYS.length) return
        i = 0
        if (typeof callback === 'string') this[callback]()
        if (typeof callback === 'function') callback.call(this)
      }
    }
  }
}