key seq

const TIMEOUT = 500

patterns = {
	's-r': [83, 82]
}

handler = e => {
	// console.log(e.which)
	clearTimeout(handler.timer)
	handler.keys[e.which] = true
	const result = Object.entries(patterns).find(([seq, pattern]) => pattern.every(key => handler.keys.hasOwnProperty(key)))
	if (result) {
		window.dispatchEvent(new CustomEvent('keyseq', { detail: result[0] }))
		handler.keys = {}
    }
	handler.timer = setTimeout(() => {
		handler.keys = {}
		console.log('CLEAR BUFFER')
    }, TIMEOUT)
}
handler.timer = null
handler.keys = {}

window.addEventListener('keydown', handler)