Simple javascript cache

How to create a basic javascript cache

const cache = {};

function addToCache(key, value, maxTimeInSeconds) {
    cache[key] = {
        value,
        expiry: Date.now() + maxTimeInSeconds * 1000
    };
}

function getFromCache(key: string) {
    const cacheItem = cache[key];
    if (cacheItem && cacheItem.expiry > Date.now()) {
        return cacheItem.value;
    } else {
        delete cache[key];
        return undefined;
    }
}

// Usage
addToCache("key", "value", 10);
getFromCache("key");