Prefetching Data:
Next.js allows you to prefetch data for a page or component using the getStaticProps or getServerSideProps functions. These functions are used to fetch data at build time or request time, respectively. By prefetching data, Next.js can pre-render pages with the necessary data, making them available immediately when requested by the user.
For example, if you have a blog with a list of posts, you can prefetch the list of posts data when the user navigates to the blog page. This way, when the user lands on the blog page, the posts are already available, reducing the time needed to load and render the content.
Prefetching Code:
Next.js also supports prefetching code, specifically JavaScript bundles for dynamic imports. When you dynamically import a module using import() or dynamic(), Next.js can prefetch the module’s JavaScript bundle in the background while the user is interacting with the page. This ensures that when the imported module is needed, it can be loaded quickly without any delay.
For example, if you have a modal component that is dynamically imported and only appears when the user clicks a button, Next.js can prefetch the JavaScript bundle for the modal component in anticipation of the user action. As a result, when the user clicks the button to open the modal, the modal appears instantly without any noticeable delay caused by loading the JavaScript bundle.
Impact on Performance:
Prefetching in Next.js can have a significant impact on performance by reducing latency and improving perceived load times. By fetching resources ahead of time, Next.js minimizes the time required to fetch and render content, leading to a smoother and faster user experience.
However, it’s essential to use prefetching judiciously to avoid unnecessary network requests and resource consumption. Prefetching too many resources at once can overload the network and slow down the initial page load. Therefore, it’s crucial to prioritize prefetching based on the user’s navigation patterns and the criticality of the resources.