Next.js provides two main rendering strategies: Static Site Generation (SSG) and Server-Side Rendering (SSR). Choosing the right approach can significantly impact your application’s performance, SEO, and overall user experience. In the article, I will dive into the differences between SSG and SSR, and explore when to use each one.
Understanding Static Site Generation (SSG)
Static Site Generation is a process where the HTML pages are pre-rendered at build time. This means that when a user visits your website, they receive a fully rendered page without the need for any client-side JavaScript execution.
Advantages of Static Site Generation
- Improved Performance: Since the HTML is pre-rendered, the initial load time is incredibly fast, resulting in a better user experience.
- Better SEO: Search engines can easily crawl and index pre-rendered content, improving your website’s visibility and organic traffic.
- Reduced Server Load: With no server-side rendering required, there’s less load on your servers, making it more cost-effective for high-traffic websites.
When to Use Static Site Generation
Static Site Generation is an excellent choice for:
- Content-Heavy Websites: Blogs, documentation sites, and marketing pages with mostly static content.
- E-Commerce Sites: Product catalogs and listings that don’t require real-time data updates.
- Personal Portfolios and Landing Pages: Sites with little to no dynamic content.
Here’s an example of how you can use SSG in Next.js with the getStaticProps
function:
// pages/blog/[slug].js import { getAllPosts, getPostBySlug } from '../../lib/api' export async function getStaticProps({ params }) { const postData = getPostBySlug(params.slug) return { props: { postData } } } export async function getStaticPaths() { const paths = getAllPosts().map((post) => ({ params: { slug: post.slug } })) return { paths, fallback: false } } export default function Post({ postData }) { // Render post with postData prop }
Understanding Server-Side Rendering (SSR)
Server-Side Rendering is a technique where the initial page load is rendered on the server, and the resulting HTML is sent to the client. Subsequent page navigations are handled client-side using JavaScript.
Advantages of Server-Side Rendering
- Dynamic Content Support: SSR is ideal for applications that require real-time data updates or personalized experiences.
- Initial Load Performance: The initial page load is faster than client-side rendering, as the HTML is pre-rendered on the server.
- SEO Friendly: Search engines can crawl and index server-rendered content.
When to Use Server-Side Rendering
SSR is the way to go when:
- Building Real-Time Applications: Apps that require frequent data updates, like live dashboards or chat applications.
- Handling User-Specific Content: E-commerce websites with personalized recommendations or user profiles.
- Working with Sensitive Data: Applications that deal with sensitive user data that shouldn’t be exposed on the client-side.
Here’s an example of how you can use SSR in Next.js with the getServerSideProps
function:
// pages/user/[id].js import { getUserData } from '../../lib/api' export async function getServerSideProps({ params }) { const userData = await getUserData(params.id) return { props: { userData } } } export default function UserProfile({ userData }) { // Render user profile with userData prop }
Hybrid Approach: Using Static Site Generation with Revalidation and ISR
Next.js also provides a hybrid approach that combines the benefits of SSG and SSR. This is achieved through Incremental Static Regeneration (ISR) and Revalidation.
Incremental Static Regeneration (ISR)
With ISR, you can statically generate pages at build time, but also periodically regenerate pages after deployment based on incoming requests. This allows you to maintain the performance benefits of SSG while ensuring your content stays up-to-date.
Here’s an example of how you can use ISR in Next.js:
// pages/blog/[slug].js export async function getStaticProps({ params }) { const postData = getPostBySlug(params.slug) return { props: { postData }, revalidate: 60 // Regenerate the page every 60 seconds } }
Revalidation
Revalidation is a feature that allows you to update a statically generated page after its initial build. When a user requests a page that needs revalidation, Next.js will check if the data is still up-to-date. If not, it will regenerate the page with the latest data before serving it to the user.
You can configure revalidation at the page level using the revalidate
option in getStaticProps
, or at the application level using the unstable_revalidate
option in next.config.js
.
// next.config.js module.exports = { unstable_revalidate: 60 // Revalidate every 60 seconds }
Choosing the Right Approach
When deciding between SSG, SSR, or a hybrid approach, consider the following factors:
- Data Requirements: If your application relies heavily on real-time, personalized, or sensitive data, SSR is likely the better choice. If your data is mostly static and infrequently updated, SSG can provide better performance and SEO benefits.
- Performance and Scalability: For high-traffic websites with mostly static content, SSG can significantly reduce server load and improve performance. SSR may be more suitable for applications with lower traffic and more dynamic content.
- Content Updates: If your content updates frequently, a hybrid approach with ISR or revalidation can ensure your users receive the latest data while maintaining the benefits of SSG.
- SEO Considerations: Both SSG and SSR are SEO-friendly, but SSG can provide a slight advantage for content-heavy websites due to its pre-rendered HTML.
Remember, you’re not limited to a single approach. Next.js allows you to mix and match rendering strategies within the same application, enabling you to choose the best approach for each page or component.