Very small (376B minified) implementation of Konami code in TypeScript (0BSD licensed)

konami.ts

/*!
 * BSD Zero Clause License
 * Copyright (c) Cynthia Rey
 * SPDX-License-Identifier: 0BSD
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
 * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

// Hack to not be annoyed by number vs NodeJS.Timeout shenanigans
type Timeout = ReturnType<typeof setTimeout>

let keys: string[] = ['ArrowUp', 'ArrowUp', 'ArrowDown', 'ArrowDown', 'ArrowLeft', 'ArrowRight', 'ArrowLeft', 'ArrowRight', 'B', 'A']
let current: number = 0
let timeout: Timeout | null = null

window.addEventListener('keydown', (e) => {
	if (timeout) {
		clearTimeout(timeout)
		timeout = null
	}

	// If modifier is pressed, ignore
	if (e.ctrlKey || e.shiftKey || e.altKey || e.metaKey) {
		current = 0
		return
	}

	// Check the sequence
	let k = e.key.length > 1 ? e.key : e.key.toUpperCase()
	if (keys[current] === k) {
		current++
	}

	// We got the code!
	if (keys.length === current) {
		current = 0
		onKonamiCode()
	} else {
		// Consider the attempt abandoned if no key is pressed within a second
		timeout = setTimeout(() => {
			current = 0
			timeout = null
		}, 1e3)
	}
})

function onKonamiCode () {
	console.log('nerd')
}