In Next.js, choosing between cache: 'no-store' and cache: 'force-cache' in SSR depends on your data freshness needs. Using force-cache with revalidate improves performance but delays updates, making it unsuitable for real-time apps like chats or stock trackers. On the other hand, no-store ensures every request fetches fresh data, crucial for dynamic dashboards or live updates. While force-cache works well for semi-static content like blogs or product listings, no-store maintains SSR's true purpose—delivering up-to-date content instantly. Always match your caching strategy to your app's real-time requirements.

In JavaScript, callback and higher-order functions (HOF) are fundamental to functional programming. A callback function is a function that is passed as an argument to another function and gets executed later, commonly used in event handlers or API responses. On the other hand, a higher-order function is a function that either takes another function as an argument or returns a function, such as map(), filter(), and reduce(). These concepts make code more modular, reusable, and expressive, playing a crucial role in JavaScript's asynchronous and functional programming paradigms.