Saved from https://www.sohamkamani.com/blog/javascript-localstorage-with-ttl-expiry/

setWithExpiry

function setWithExpiry(key, value, ttl) {
	const now = new Date()

	// `item` is an object which contains the original value
	// as well as the time when it's supposed to expire
	const item = {
		value: value,
		expiry: now.getTime() + ttl,
	}
	localStorage.setItem(key, JSON.stringify(item))
}