Next Js Crash Course

Notes from Next.js Crash Course from Traversy Media YouTube channel.

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Requirements

You should know React and be familiar with:

• Creating components
• Using Jsx
• Passing props
• Using state

You should have install:

• Node.js al least version 16.8 or later

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What is Next.js?

Next is a React frontend development web framework created by Vercel that enables functionality such as SSR and SSG.

SSR

Unlike a client side framework, Next.js is optimized for SEO and performance. Also you get client side routing

Benefits

• Easy page routing, create a file for a page and put it in the pages folder and that page will be automatically rendered.
• API Routes, create API routes within the next file structure. You can use other backends.
• TypeScript and Sass, out of the box.
• SSG, export static website
• Easy deployment, developed and hosted in Vercel or any node.js hosting

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Usage

Version 13

npx create-next-app@latest

Version 12

npx create-next-app@12 app-name && cd app-name && npm i next@12

Scripts

• dev run development
• build generate build ready for production
• start generate build and run in local env

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Folder and files

• public static files, images, styles, icons
• styles global styles and specific css file for pages and components, e.g. Page.module.css
  • Can’t import global styles in pages or components
  • import styles from '../styles/Home.module.css
• pages routing system, put pages inside the pages folder. The filename is the same for the url. e.g. pages/about.js ⇒ http://localhost:3000/about
• pages/_app.js Wraps around all of your page components. You can add a layout, show a header, footer, etc.
  • Lowercase for pages file name.

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Layout and CSS modules

To display a layout around, create a new layout file and import in pages/_app.js

• components/Layout.js Pascal case for components file name.
  • Create as rafce and add children as a prop

// components/Layout.js
import styles from '../styles/Layout.module.css'

const Layout = ({ children }) => {
  return (
    <div className={styles.container}>
      <main className={styles.main}>{children}</main>
    </div>
  )
}

export default Layout

// pages/_app.js
import Layout from '../components/Layout'
import '../styles/globals.css'

function MyApp({ Component, pageProps }) {
  return (
    <Layout>
      <Component {...pageProps} />
    </Layout>
  )
}

export default MyApp

---

Components

As the same in React, all components should have a single parent element.

Head

import Head from 'next/head'

The component to add title and meta tags, the same way as in an HTML file.

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Navigation and links

• styles/Nav.module.css
• components/Nav.js
• In the component import Link from 'next/link' for anchor tags, add links for Home and About

import Link from 'next/link'
import styles from '../styles/Nav.module.css'
const Nav = () => {
  return (
    <nav className={styles.nav}>
      <ul>
        <li>
          <Link href='/'>Home</Link>
        </li>
        <li>
          <Link href='/about'>About</Link>
        </li>
      </ul>
    </nav>
  )
}

export default Nav

• Import Nav component into Layout.js just before the .containerdiv tag.

---

Custom document

Augment body and html tags.

Resource:

Routing: Custom Document

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Fetch data

• getStaticProps, allow to fetch at build time
• getServerSideProps, allow to fetch on every request (slow)
• getStaticPaths, dynamic generate paths based on the data we’re fetching

Usage

Can be used at the top or bottom of the file.

export const getStaticProps = async () => {
  const res = await fetch(`https://jsonplaceholder.typicode.com/posts?_limit=6`)
  const articles = await res.json()
	// return props object
  return {
    props: {
      articles,
    },
  }
}

Return a props object and the data we want to pass.

---

Nested routing

• Create files and folders structure
  • pages/article/[id]/index.js

// index.js, base code to fix 404 page
const article = () => {
	return <p>This is an article</p>
}
export default article

Use data fecthing method that NextJs provide to pages

• getServerSideProps fetch the data at the time of request, rather than getStaticProps that fetch at build time
• Can get pass in a context to get the id of the url context.params.id
• Return an object with props

export const getServerSideProps = async (context) => {
  const res = await fetch(
    `https://jsonplaceholder.typicode.com/posts/${context.params.id}`
  )
  const article = await res.json()
  return {
    props: {
      article,
    },
  }
}

getStaticProps and getStaticPaths

Dynamic generate the path with the data

export const getStaticProps = async (context) => {
  const res = await fetch(
    `https://jsonplaceholder.typicode.com/posts/${context.params.id}`
  )
  const article = await res.json()
  return {
    props: {
      article,
    },
  }
}

// Get all posts
export const getStaticPaths = async () => {
  const res = await fetch('https://jsonplaceholder.typicode.com/posts/')
  const articles = await res.json()

	// generate paths structure
  const ids = articles.map((article) => article.id)
  const paths = ids.map((id) => ({ params: { id: id.toString() } }))

  return {
    // paths: {params: {id: '1', id: '2'}}
    paths,
    fallback: false,
  }
}

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Generate static website

Edit package.json and edit build script to add next export

"scripts": {
    "build": "next build && next export",

• Run npm run build to generate the static out folder
• Run serve -s out -p 8000
  • Requirement npm i -g serve

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API routes

Create API routes, a function that take a request and a response.

Respond with a specific status code and respond with a specific data.

Similar to Express, any backend REST API.

Files and folders

Create a new data.js file in the root folder for the data.

Create as many files as you need based on the functions required: Get all posts, Get a single post.

• pages/api/articles/index.js
• pages/api/articles/[id].js

// index.js get all posts
import { articles } from '../../../data'

export default function handler(req, res) {
  res.status(200).json(articles)
}

All posts are accessible from http://localhost:3000/api/articles/

// [id].js
import { articles } from '../../../data'

export default function handler({ query: { id } }, res) {
  const filtered = articles.filter((article) => article.id === id)

  if (filtered.length > 0) {
    res.status(200).json(filtered[0])
  } else {
    res
      .status(404)
      .json({ message: `Article with the id of ${id} is not found.` })
  }
}

Access a single post from http://localhost:3000/api/articles/1

Use routes

💡 Only absolute URLs are supported, need to create a config file.

• root/config/index.js

const dev = process.env.NODE_ENV !== 'production'
export const server = dev ? 'http://localhost:3000' : 'https://yourwebsite.com'

And then import to pages/index.js as server.

// pages/index.js
import { server } from '../config'
...

// fetch from local API
export const getStaticProps = async () => {
  const res = await fetch(`${server}/api/articles`)
  const articles = await res.json()
  return {
    props: {
      articles,
    },
  }
}

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Meta component

Create a new Meta component to use for all pages and update title, description where needed.

Meta component