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diff --git a/content/pages.mdx b/content/pages.mdx new file mode 100644 index 0000000..0e26bf8 --- /dev/null +++ b/content/pages.mdx @@ -0,0 +1,237 @@ +--- +title: Next.js Pages +date: 2025-03-21 +description: Dive into the details of Next.js Pages with examples, dynamic routing, pre-rendering strategies like Static Generation and SSR, and pro tips for building fast, SEO-friendly web apps. Packed with insights and tricks from my latest project! +tags: ['nextjs', 'web'] +image: /images/blog/pages.png +author: You +--- + +In Next.js, a **page** is a [React Component](https://react.dev/reference/react/Component) exported from a `.js`, `.jsx`, `.ts`, or `.tsx` file in the `pages` directory. Each page is associated with a route based on its file name. + +**Example**: If you create `pages/about.js` that exports a React component like below, it will be accessible at `/about`. + +```javascript +function About() { + return <div>About</div> +} + +export default About +``` + +### Pages with Dynamic Routes + +Next.js supports pages with dynamic routes. For example, if you create a file called `pages/posts/[id].js`, then it will be accessible at `posts/1`, `posts/2`, etc. + +> To learn more about dynamic routing, check the [Dynamic Routing documentation](https://nextjs.org/docs/routing/dynamic-routes). + +## Pre-rendering + +By default, Next.js **pre-renders** every page. This means that Next.js generates HTML for each page in advance, instead of having it all done by client-side JavaScript. Pre-rendering can result in better performance and SEO. + +Each generated HTML is associated with minimal JavaScript code necessary for that page. When a page is loaded by the browser, its JavaScript code runs and makes the page fully interactive. (This process is called _hydration_.) + +### Two forms of Pre-rendering + +Next.js has two forms of pre-rendering: **Static Generation** and **Server-side Rendering**. The difference is in **when** it generates the HTML for a page. + +- [**Static Generation (Recommended)**](#static-generation-recommended): The HTML is generated at **build time** and will be reused on each request. +- [**Server-side Rendering**](#server-side-rendering): The HTML is generated on **each request**. + +Importantly, Next.js lets you **choose** which pre-rendering form you'd like to use for each page. You can create a "hybrid" Next.js app by using Static Generation for most pages and using Server-side Rendering for others. + +We **recommend** using **Static Generation** over Server-side Rendering for performance reasons. Statically generated pages can be cached by CDN with no extra configuration to boost performance. However, in some cases, Server-side Rendering might be the only option. + +You can also use **Client-side Rendering** along with Static Generation or Server-side Rendering. That means some parts of a page can be rendered entirely by client side JavaScript. To learn more, take a look at the [Data Fetching](https://nextjs.org/docs/basic-features/data-fetching/client-side) documentation. + +## Static Generation (Recommended) + +If a page uses **Static Generation**, the page HTML is generated at **build time**. That means in production, the page HTML is generated when you run `next build` . This HTML will then be reused on each request. It can be cached by a CDN. + +In Next.js, you can statically generate pages **with or without data**. Let's take a look at each case. + +### Static Generation without data + +By default, Next.js pre-renders pages using Static Generation without fetching data. Here's an example: + +```javascript +function About() { + return <div>About</div> +} + +export default About +``` + +Note that this page does not need to fetch any external data to be pre-rendered. In cases like this, Next.js generates a single HTML file per page during build time. + +### Static Generation with data + +Some pages require fetching external data for pre-rendering. There are two scenarios, and one or both might apply. In each case, you can use a special function Next.js provides: + +1. Your page **content** depends on external data: Use `getStaticProps`. +2. Your page **paths** depend on external data: Use `getStaticPaths` (usually in addition to `getStaticProps`). + +#### Scenario 1: Your page **content** depends on external data + +**Example**: Your blog page might need to fetch the list of blog posts from a CMS (content management system). + +```javascript +// TODO: Need to fetch `posts` (by calling some API endpoint) +// before this page can be pre-rendered. +function Blog({ posts }) { + return ( + <ul> + {posts.map((post) => ( + <li>{post.title}</li> + ))} + </ul> + ) +} + +export default Blog +``` + +To fetch this data on pre-render, Next.js allows you to `export` an `async` function called `getStaticProps` from the same file. This function gets called at build time and lets you pass fetched data to the page's `props` on pre-render. + +```javascript +function Blog({ posts }) { + // Render posts... +} + +// This function gets called at build time +export async function getStaticProps() { + // Call an external API endpoint to get posts + const res = await fetch('https://.../posts') + const posts = await res.json() + + // By returning { props: { posts } }, the Blog component + // will receive `posts` as a prop at build time + return { + props: { + posts + } + } +} + +export default Blog +``` + +To learn more about how `getStaticProps` works, check out the [Data Fetching documentation](https://nextjs.org/docs/basic-features/data-fetching/get-static-props). + +#### Scenario 2: Your page paths depend on external data + +Next.js allows you to create pages with **dynamic routes**. For example, you can create a file called `pages/posts/[id].js` to show a single blog post based on `id`. This will allow you to show a blog post with `id: 1` when you access `posts/1`. + +> To learn more about dynamic routing, check the [Dynamic Routing documentation](https://nextjs.org/docs/routing/dynamic-routes). + +However, which `id` you want to pre-render at build time might depend on external data. + +**Example**: suppose that you've only added one blog post (with `id: 1`) to the database. In this case, you'd only want to pre-render `posts/1` at build time. + +Later, you might add the second post with `id: 2`. Then you'd want to pre-render `posts/2` as well. + +So your page **paths** that are pre-rendered depend on external data**.** To handle this, Next.js lets you `export` an `async` function called `getStaticPaths` from a dynamic page (`pages/posts/[id].js` in this case). This function gets called at build time and lets you specify which paths you want to pre-render. + +```javascript +// This function gets called at build time +export async function getStaticPaths() { + // Call an external API endpoint to get posts + const res = await fetch('https://.../posts') + const posts = await res.json() + + // Get the paths we want to pre-render based on posts + const paths = posts.map((post) => ({ + params: { id: post.id } + })) + + // We'll pre-render only these paths at build time. + // { fallback: false } means other routes should 404. + return { paths, fallback: false } +} +``` + +Also in `pages/posts/[id].js`, you need to export `getStaticProps` so that you can fetch the data about the post with this `id` and use it to pre-render the page: + +```javascript +function Post({ post }) { + // Render post... +} + +export async function getStaticPaths() { + // ... +} + +// This also gets called at build time +export async function getStaticProps({ params }) { + // params contains the post `id`. + // If the route is like /posts/1, then params.id is 1 + const res = await fetch(`https://.../posts/${params.id}`) + const post = await res.json() + + // Pass post data to the page via props + return { props: { post } } +} + +export default Post +``` + +To learn more about how `getStaticPaths` works, check out the [Data Fetching documentation](https://nextjs.org/docs/basic-features/data-fetching/get-static-paths). + +### When should I use Static Generation? + +We recommend using **Static Generation** (with and without data) whenever possible because your page can be built once and served by CDN, which makes it much faster than having a server render the page on every request. + +You can use Static Generation for many types of pages, including: + +- Marketing pages +- Blog posts +- E-commerce product listings +- Help and documentation + +You should ask yourself: "Can I pre-render this page **ahead** of a user's request?" If the answer is yes, then you should choose Static Generation. + +On the other hand, Static Generation is **not** a good idea if you cannot pre-render a page ahead of a user's request. Maybe your page shows frequently updated data, and the page content changes on every request. + +In cases like this, you can do one of the following: + +- Use Static Generation with **Client-side Rendering:** You can skip pre-rendering some parts of a page and then use client-side JavaScript to populate them. To learn more about this approach, check out the [Data Fetching documentation](https://nextjs.org/docs/basic-features/data-fetching/client-side). +- Use **Server-Side Rendering:** Next.js pre-renders a page on each request. It will be slower because the page cannot be cached by a CDN, but the pre-rendered page will always be up-to-date. We'll talk about this approach below. + +## Server-side Rendering + +> Also referred to as "SSR" or "Dynamic Rendering". + +If a page uses **Server-side Rendering**, the page HTML is generated on **each request**. + +To use Server-side Rendering for a page, you need to `export` an `async` function called `getServerSideProps`. This function will be called by the server on every request. + +For example, suppose that your page needs to pre-render frequently updated data (fetched from an external API). You can write `getServerSideProps` which fetches this data and passes it to `Page` like below: + +```javascript +function Page({ data }) { + // Render data... +} + +// This gets called on every request +export async function getServerSideProps() { + // Fetch data from external API + const res = await fetch(`https://.../data`) + const data = await res.json() + + // Pass data to the page via props + return { props: { data } } +} + +export default Page +``` + +As you can see, `getServerSideProps` is similar to `getStaticProps`, but the difference is that `getServerSideProps` is run on every request instead of on build time. + +To learn more about how `getServerSideProps` works, check out our [Data Fetching documentation](https://nextjs.org/docs/basic-features/data-fetching/get-server-side-props) + +## Summary + +We've discussed two forms of pre-rendering for Next.js. + +- **Static Generation (Recommended):** The HTML is generated at **build time** and will be reused on each request. To make a page use Static Generation, either export the page component, or export `getStaticProps` (and `getStaticPaths` if necessary). It's great for pages that can be pre-rendered ahead of a user's request. You can also use it with Client-side Rendering to bring in additional data. +- **Server-side Rendering:** The HTML is generated on **each request**. To make a page use Server-side Rendering, export `getServerSideProps`. Because Server-side Rendering results in slower performance than Static Generation, use this only if absolutely necessary.
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