プロジェクトの作成

mkdir proj01
cd proj01
npm init -y
npm install --save react react-dom next
mkdir pages

package.json の改造

package.json

{
  "name": "proj01",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
   "dev": "next",
    "build": "next build",
    "start": "next start"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "next": "^12.2.0",
    "react": "^18.2.0",
    "react-dom": "^18.2.0"
  }
}

コードの作成

フォルダー構造

$ tree pages/
pages/
├── Header.js
├── Layout.js
├── index.js
└── pets.js

pages/index.js

import Layout from "./Layout"

export default function Index() {
  return (
    <Layout>
      <div>
        <h1>Hello everyone!</h1>
	<p>May/23/2022 PM 15:50</p>
      </div>
    </Layout>
  )
}

pages/pets.js

import Layout from "./Layout";
import fetch from "isomorphic-unfetch";

export default function Pets(props) {
  return (
    <Layout>
      <div>
        <h1>Pets!</h1>
	<table>
	<thead>
	<tr>
	<th>id</th>
	<th>name</th>
	<th>category</th>
	</tr>
	</thead>
	<tbody>
          {props.pets.map(pet => (
        <tr id={pet.id}>
	<td>{pet.id}</td>
	<td>{pet.name}</td>
	<td>{pet.category}</td>
	</tr>
          ))}
	</tbody>
	</table>
<p>May/23/2022 PM 15:50</p>
      </div>
    </Layout>
  );
}

Pets.getInitialProps = async function() {
  const res = await fetch(
    `https://pet-library.moonhighway.com/api/pets`
  );
  const data = await res.json();
  return {
    pets: data
  };
};

pages/Layout.js

import Header from "./Header"

export default function Layout(props) {
  return (
    <div>
<Header />
{props.children}
    </div>
  )
}

pages/Header.js

import Link from "next/link"

export default function Header(){
	return (
	<div>
		<Link href="/">
		<a>Home</a>
		</Link>
		&nbsp;
		&nbsp;
		&nbsp;
		<Link href="/pets">
		<a>Pets</a>
		</Link>
	</div>
	)
}

サーバーの起動

npm run dev

ブラウザーで
http://localhost:3000
にアクセス