sandrino-di-mattia

Principal Architect

Sandrino Di Mattia

I stream, blog, and make youtube videos about tech stuff. I love coding, I love AI, and I love building stuff!

Staff Developer Advocate

Juan Cruz Martinez

Learn how (and where) to authenticate your user in the different deployment models that exist for Next.js

The Ultimate Guide to Next.js Authentication with Auth0

37590801?s=460&v=4

A software engineer who dreams about non-electric sheep and autonomous vehicles and likes to champion security.

Software Engineer

Dan Arias

Learn how to use Next.js to create server-side rendered React applications.



In this tutorial series, you'll be provided with a practical introduction to how Next.js can help you build web applications.

Created by [Vercel, a cloud company for hosting frontends and serverless functions](https://vercel.com/home), Next.js is a React framework capable of creating applications that run both on the client and the server, otherwise known as Universal JavaScript applications. This framework helps you build universal apps faster by streamlining basic features like client-side routing and page layout while simplifying advance features like server-side rendering and code splitting.

In this first part of the series, you'll learn how to create pages and a page layout [using Next.js 9](https://nextjs.org/blog/next-9), the most recent framework version at the time of writing. [Familiarity with the React library](https://auth0.com/blog/react-tutorial-building-and-securing-your-first-app/) is recommended.

## Getting Started

To start, you need to bootstrap a React project with `next` as a dependency. Anywhere in your system, create a folder named `whatabyte` and make it your current directory:

```bash
mkdir whatabyte
cd whatabyte
```

Then, initialize a default Node.js project under the `whatabyte` directory and install core dependencies by issuing these commands:

```bash
npm init -y
npm install --save react react-dom next
```

As the name suggests, `next` is the package that will allow you to use the Next.js framework in your project with all of its modules, components, and dependencies.

Next.js is flexible but has one major structural requirement for it to work. Every Next.js project needs to have a `pages` subdirectory child to the project directory. Therefore, create a new `pages` subdirectory like so:

```bash
mkdir pages
```

Every page of your web app will be defined as a React component in a JavaScript file under the `pages` subdirectory. For example, the file `index.js` represents the root path, `/` and a file named `user.js` represents the `/user` path. You'll get a more detailed explanation of these mechanics in the next section.

To make running and building your Next.js application easy, replace the NPM scripts of your `package.json` with the following:

```json
{
  //...
  "scripts": {
    "dev": "next",
    "build": "next build",
    "start": "next start"
  },
  //...
}
```

Save the changes made to `package.json`. To run the project, execute this command in the terminal:

```bash
npm run dev
```

Head to [`http://localhost:3000/`](http://localhost:3000/) and bask in the glory of a `404` error. You haven't done anything wrong. This error shows up because the `pages` directory is empty. It needs an `index.js` file inside to render the default `/` home route. You'll do that... Next!

## Creating Your First Next.js Page

To understand how Next.js works, it helps to think about creating websites the classical way using HTML pages. The `index.html` file is the entry point of a website and it contains logic that takes the visitor to any other pages, like `about.html` and `profile.html`.

With Next.js, each page is represented by a JavaScript file under the `pages` subdirectory. Each file, instead of having HTML templates, exports a React component that is used by Next.js to render the page with the default root route being `index.js`. Go ahead and create this file under `pages` subdirectory:

```bash
touch pages/index.js
```

* Windows PowerShell:

```bash
ni pages/index.js
```

Populate `index.js` with this code:


```javascript
// pages/index.js

const Index = () => (
  <div>
    <p>Thank u, next</p>
  </div>
);

export default Index;
```

Without having to restart the app, Next.js detects the new `index.js` and the exported `Index` component and updates the view in the browser automatically.

![Next.js index page](https://images.ctfassets.net/23aumh6u8s0i/2bXaYCcMmJDNz0US5biyQb/62f0e3dbcc6d0cfe90e1e8d8f69b24dd/nextjs-practical-introduction_nextjs-index-page)

If you were using `create-react-app` to build your React application, you'd be looking here at rendering an `App` component instead. The `App` component is the parent or shell component for the whole application. With Next.js, you can think of that component as being implied through the `pages` subdirectory and hierarchy.

To achieve a uniform core interface for each page, you'd want to have a common layout that includes a header, a content container, and a navigation bar. This can be easily done with Next just like you'd do it with `create-react-app`: using components.

## Creating a Next.js Layout Using React Components

Under the `whatabyte` root directory, create a `components` directory:

```bash
mkdir components
```

The name of this directory could be really anything, but it makes sense to stick with well-understood file structure names that make it easier for anyone else to understand the structure of your application.

You need three components for creating a layout:

* `Layout` to hold the core view in place
* `Header` to provide a standard header to all views
* `NavBar` to provide navigation buttons

Thus, create the following files under the `components` directory:

* `Layout.js`
* `Header.js`
* `NavBar.js`

```bash
touch components/Layout.js components/Header.js components/NavBar.js
```

* Windows PowerShell:

```bash
ni components/Layout.js, components/Header.js, components/NavBar.js
```

Open `Header.js` and add the following code to it:

```javascript
// components/Header.js

const headerStyle = {
  backgroundColor: "blue",
  color: "white",
  width: "100%",
  height: "50px"
};

const Header = () => (
  <div className="Header" style={headerStyle}>
    HEADER
  </div>
);

export default Header;
```

In `NavBar.js` add the following:

```javascript
// components/NavBar.js

const navBarStyle = {
  backgroundColor: "red",
  color: "white",
  width: "100%",
  height: "60px"
};

const NavBar = () => (
  <div className="NavBar" style={navBarStyle}>
    NAVBAR
  </div>
);

export default NavBar;
```

In `Layout.js`, use the `Header` and `NavBar` components to render any content passed through `props.children` within a `Content` container:

```javascript
// components/Layout.js

import Header from "./Header";
import NavBar from "./NavBar";

const layoutStyle = {
  display: "flex",
  flexDirection: "column",
  height: "100%",
  width: "100%"
};

const contentStyle = {
  flex: 1,
  display: "flex",
  flexDirection: "column"
};

const Layout = props => (
  <div className="Layout" style={layoutStyle}>
    <Header />
    <div className="Content" style={contentStyle}>
      {props.children}
    </div>
    <NavBar />
  </div>
);

export default Layout;
```

These three components use inline CSS styling to give improve their structure and presentation.

Finally, update `index.js` to use the `Layout` component:

```javascript
// pages/index.js

import Layout from "../components/Layout";

const Index = () => <Layout>Welcome to WHATABYTE!</Layout>;

export default Index;
```  

![Next.js index page using a layout component](https://images.ctfassets.net/23aumh6u8s0i/69v0dEitl6ISUXJtGPylY/7b08e470423209df73b4c8340384968b/nextjs-practical-introduction_nextjs-index-page-using-a-layout-component)

> The look and feel of the interface will improve in the next part of this tutorial.

In the browser, the index page now shows a blue box serving as a header, a white box with a message serving as content, and a red box serving as the navigation bar. With a layout in place, you are ready to create more pages with a consistent structure.

## Creating More Pages Using Next.js

The _WHATABYTE_ app has four core views:

* Explore: To show trending restaurants and dishes
* Near Me: To show restaurants near the user
* My Cart: To show the orders of the user
* Profile: To show the user information such as name, address, and billing data

As you may be thinking, you'll need to add new files under the `pages` directory to represent each of these pages. You are right. The plan here is to create a route for each view:

* `/explore`
* `/nearme`
* `/mycart`
* `/profile`

To create these views, create the following files under the `pages` directory and add their respective content:

```bash
touch pages/explore.js pages/nearme.js pages/mycart.js pages/profile.js
```

* Windows PowerShell:

```bash
ni pages/explore.js, pages/nearme.js, pages/mycart.js, pages/profile.js
```

- `explore.js`:

```javascript
// pages/explore.js

import Layout from "../components/Layout";

const ExploreView = props => <Layout>{`Explore View`}</Layout>;

export default ExploreView;
```

- `nearme.js`:

```javascript
// pages/nearme.js

import Layout from "../components/Layout";

const NearMeView = props => <Layout>{`Near Me View`}</Layout>;

export default NearMeView;
```

- `mycart.js`:

```javascript
// pages/mycart.js

import Layout from "../components/Layout";

const MyCartView = props => <Layout>{`My Cart View`}</Layout>;

export default MyCartView;
```

- `profile.js`:

```javascript
// pages/profile.js

import Layout from "../components/Layout";

const ProfileView = props => <Layout>{`Profile View`}</Layout>;

export default ProfileView;
```

In the browser, you can visit [`http://localhost:3000/explore`](http://localhost:3000/explore) and see the new Explore page up and running! You can try any of the other paths as well.

<include src="TweetQuote" quoteText="Learn how to bootstrap a Next.js application to create pages and a page layout."/>

## Get Your Head In the Next.js Game

Your Next.js pages need to have a document title shown on the page tab or window title bar of the browser. To add a document title, you need to use the [`<title>`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/title) HTML element which can only be used within a web page's `<head>` block.

Next.js pages are created with a `<head>` block that has sensible defaults such as the following:

```html
<head>
  <title class="next-head"></title>
  <meta charset="utf-8" class="next-head">
  <meta
    name="viewport"
    content="width=device-width,minimum-scale=1,initial-scale=1"
    class="next-head">
</head>
```

However, notice that the `title` tag is empty. To modify the `head` block, Next.js offers a [built-in `Head` component](https://github.com/zeit/next.js/#populating-head) in the `next/head` module which appends elements to the `<head>` block of a page. To modify the document title, you'd nest a `title` HTML element within the `Head` component.

Since you need the document title to be present on every page, the `<head>` block should be modified within the `Layout` component template. Open `components/Layout.js` and update its content as follows:

```javascript
// components/Layout.js

import Head from "next/head";

// Component imports remain the same

// Style objects already defined

const Layout = props => (
  <div className="Layout" style={layoutStyle}>
    <Head>
      <title>WHATABYTE</title>
    </Head>

    <Header />
    <div className="Content" style={contentStyle}>
      {props.children}
    </div>
    <NavBar />
  </div>
);

export default Layout;
```

The browser tab or window hosting your page should now reflect the "WHATABYTE" title.

The `<head>` block can also contain other important metadata (data that describes data) like scripts, stylesheets, character encoding, name, and much more.

> For more information, visit the [`<head>` block](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/head) and [metadata](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta#Attributes) MDN docs.

<include src="TweetQuote" quoteText="Learn how to get started with Next.js, a universal JavaScript framework based on React."/>

## Next Steps

The current layout of the application is not working as it should. The `.Content` container, within the `Layout` component, is expected to stretch out to fill the space left by the `Header` and `NavBar` components as its `contentStyle` object specifies the `flex: 1` CSS property. However, this flexible property depends on the height value of the its parent, the `.Layout` container.

Despite the `height` of the `.Layout` container being specified in its `layoutStyle` object as `100%`, this container is not filling out the full height of the viewport. In turn, this could only mean that its parent doesn't have a definite height.

If you open the browser Dev Tools and look at the structure of the Index page, you'll notice that the parent container for the app is a `div` element with the ID `__next`. Clicking on that element shows that it has no height or width; therefore, its descendant containers have no height value to inherit and use for dynamic sizing.

To fix this, you'd need to give the `__next` container a `height` and `width` of `100%`. But Next.js doesn't come with a default global index stylesheet like with `create-react-app`. The solution is to style components in the "Next.js way" or to use custom SCSS, which is the topic of the next second part of this tutorial.

## Recap

In this first part, you have learned how to use Next.js to create pages that integrate a page layout. Using a page layout gives your pages consistent high-level structure. To give the elements within each page better styling and positioning, you need to rely on CSS.

So far, you applied basic styling to your pages using inline style objects. However, Next.js offers more scalable and powerful mechanisms to apply styles to your pages. In the next part of this tutorial, your pages will go from this...

![Another Next.js view with basic layout](https://images.ctfassets.net/23aumh6u8s0i/2D9tCkdKRpVwyNcCJxThNf/94870998bf1d698363b2fdb6ddeb51e3/nextjs-practical-introduction_another-nextjs-view-with-basic-layout)

... to this!

![Next.js polished layout](https://images.ctfassets.net/23aumh6u8s0i/1URWqzEEl1HZEdGTmW8vD4/37d1dfb6885b42030cbd1fb789349274/nextjs-practical-introduction_nextjs-polished-layout)

### [Continue to Part 2: Next.js Styling and Theming](https://auth0.com/blog/next-js-practical-introduction-for-react-developers-part-2/)


Next.js Practical Introduction: Pages and Layout

Learn how to use Express and Pug to build a website in Node.js

Build a Website with Node.js and Express

Learn how to use Passport.js to add user authentication to a web app built with Node.js and Express.

Node.js and Express Authentication Using Passport

Learn how to use Next.js to add navigation and routing to server-side rendered React applications.



In this tutorial series, you'll be provided with a practical introduction to how Next.js can help you build web applications. 

Created by [ZEIT, a cloud company for hosting frontends and serverless functions](https://zeit.co/), Next.js is a React framework capable of creating applications that run both on the client and the server, otherwise known as Universal JavaScript applications. This framework helps you build universal apps faster by streamlining basic features like client-side routing and page layout while simplifying advance features like server-side rendering and code splitting.

Part one of this Nextjs series shows developers [how to create pages and layouts](https://auth0.com/blog/next-js-practical-introduction-for-react-developers-part-1/). In the second part of the series, you learned [how to add styling and create themes](https://auth0.com/blog/next-js-practical-introduction-for-react-developers-part-2/). In this third part of the series, you'll learn how to navigate to pages and implement routing using [using Next.js 9](https://nextjs.org/blog/next-9), the most recent framework version at the time of writing. [Familiarity with the React library](https://auth0.com/blog/react-tutorial-building-and-securing-your-first-app/) is recommended.

## Setting Up the Project

If you are starting from this part, you can get the app that was built in the previous, second part by cloning the repo and checking out the `part-2` branch:

```bash
git clone git@github.com:auth0-blog/whatabyte-next-intro.git whatabyte
cd whatabyte
git checkout part-2
```

If you haven't [connected to GitHub using SSH](https://help.github.com/en/articles/connecting-to-github-with-ssh), please clone the repo with the HTTPS URL:

```bash
git clone https://github.com/auth0-blog/whatabyte-next-intro.git whatabyte
cd whatabyte
git checkout part-2
```

The repository is cloned into the directory called `whatabyte` on your local machine. If the directory doesn't exist, it is created.

With the branch checked out, proceed to install the project dependencies:

```bash
npm install
```

Finally, execute the following command in your terminal to run the app:

```bash
npm run dev
```

To see the app in action and start following the tutorial, visit [`http://localhost:3000`](http://localhost:3000) on your browser.

## Understanding Next.js Routing

The _WHATABYTE_ app has four core routes:

* `/explore`: To show trending restaurants and dishes
* `/nearme`: To show restaurants near the user
* `/mycart`: To show the orders of the user
* `/profile`: To show the user information such as name, address, and billing data

From these four core routes, the `/explore` route will be the main route. Thus, the root path, `/`, should redirect to `/explore`.

First, to get familiar with navigation in Next.js, you'll navigate to the Explore page from the Index page by adding a hyperlink inside the content container of the Index page. You can do this easily by using the [Next.js `Link` component](https://nextjs.org/docs#with-link) inside `index.js` as follows:

```javascript
// pages/index.js
import Link from "next/link";

import Layout from "../components/Layout";

const Index = () => (
  <Layout>
    <br />
    <Link href="/explore">
      <a> Welcome to WHATABYTE! Start Exploring Now</a>
    </Link>
  </Layout>
);

export default Index;
```

The Next.js `Link` component takes a route or navigation path as the value of its `href` property. You can embed any other component within `Link` as long as that component can take an `href` prop.

After the view updates in the browser, visit [`http://localhost:3000/`](http://localhost:3000/) and click on the link. It will take you to the Explore page.

![Next.js app using the Link component](https://images.ctfassets.net/23aumh6u8s0i/p60hqwOc0JhYZ0QZfr89b/9450c893ce78d695ecd3d01ad20313bd/nextjs-practical-introduction_nextjs-app-using-link-component)

Using this link to navigate to another page is good for testing but what the app needs is navigation through the `NavBar` component. To do so, you'd need a `NavButton` component to make the creation of four navigation buttons standard and easy to maintain. 

To make the buttons look nice, you'll use the [FontAwesome icons](https://fontawesome.com/icons?d=gallery). Using another console window or tab, install the following packages:

```bash
npm i @fortawesome/fontawesome-svg-core \
  @fortawesome/free-solid-svg-icons \
  @fortawesome/react-fontawesome
```

* Windows PowerShell:

```bash
npm i @fortawesome/fontawesome-svg-core `
  @fortawesome/free-solid-svg-icons `
  @fortawesome/react-fontawesome
```

Creating the navigation bar dynamically would be much easier if you can encapsulate all of its configuration in a file. Under the `whatabyte` directory, create a `config` subdirectory:

```bash
mkdir config
```

Within that new subdirectory, create a `buttons.js` file within it:

```bash
touch config/buttons.js
```

* Windows PowerShell:

```bash
ni config/buttons.js
```

Then, populate `buttons.js` as follows:

```javascript
// config/buttons.js

import React from "react";
import { FontAwesomeIcon } from "@fortawesome/react-fontawesome";
import {
  faCompass,
  faMapMarkerAlt,
  faUser,
  faShoppingCart
} from "@fortawesome/free-solid-svg-icons";

const navButtons = [
  {
    label: "Explore",
    path: "/explore",
    icon: <FontAwesomeIcon icon={faCompass} />
  },
  {
    label: "Near Me",
    path: "/nearme",
    icon: <FontAwesomeIcon icon={faMapMarkerAlt} />
  },
  {
    label: "My Cart",
    path: "/mycart",
    icon: <FontAwesomeIcon icon={faShoppingCart} />
  },
  {
    label: "Profile",
    path: "/profile",
    icon: <FontAwesomeIcon icon={faUser} />
  }
];

export default navButtons;
```

Then, under the `components` directory, create a `NavButton.js` file that exports the `NavButton` component:

```bash
touch components/NavButton.js
```

* Windows PowerShell:

```bash
ni components/NavButton.js
```

Then, populate `NavButton.js` with the following:

```javascript
// components/NavButton.js

import Link from "next/link";

import "./NavButton.scss";

const NavButton = props => (
  <Link href={props.path}>
    <div className="NavButton">
      <div className="Icon">{props.icon}</div>
      <span className="Label">{props.label}</span>
    </div>
  </Link>
);

export default NavButton;
```

The `NavButton` needs its proper styling. Create `NavButton.scss` as a sibling file:

```bash
touch components/NavButton.scss
```

* Windows PowerShell:

```bash
ni components/NavButton.scss
```

Then, populate `NavButton.scss` with the following [style rules](https://sass-lang.com/documentation/style-rules):

```scss
// components/NavButton.scss

.NavButton {
  display: flex;
  flex-direction: column;
  justify-content: space-around;
  align-items: center;

  height: 100%;

  cursor: pointer;

  .Icon {
    font-size: 20px;
  }

  .Label {
    font-size: 12px;
    text-transform: capitalize;
  }
}
```

Import the button configuration file in the `Layout` component and pass its data as the `navButtons` props to the `NavBar` component:

```javascript
// components/Layout.js
import Head from "next/head";

import Header from "./Header";
import NavBar from "./NavBar";

import "./Layout.scss";
import "./index.scss";

import navButtons from "../config/buttons";

const Layout = props => {
  const appTitle = `> WHATABYTE`;

  return (
    <div className="Layout">
      <Head>
        <title>WHATABYTE</title>
        <meta name="viewport" content="width=device-width, initial-scale=1" />
        <meta charSet="utf-8" />
      </Head>

      <Header appTitle={appTitle} />
      <div className="Content">{props.children}</div>
      <NavBar navButtons={navButtons} />
    </div>
  );
};

export default Layout;
```

It's better for the `Layout` component to be the one responsible for passing the button configuration to the `NavBar` component as it is in charge of enforcing a consistent structure for each page of the application. If you wanted to keep `Layout` as a presentational component, then you could wrap it into a container component that passes it the button configuration data.

To render the buttons within the `NavBar` component, update the content of the `NavBar.js` file as follows:

```javascript
// components/NavBar.js

import "./NavBar.scss";
import NavButton from "./NavButton";

const NavBar = props => (
  <div className="NavBar">
    {props.navButtons.map(button => (
      <NavButton
        key={button.path}
        path={button.path}
        label={button.label}
        icon={button.icon}
      />
    ))}
  </div>
);

export default NavBar;
```

If your app is not running, execute `npm run dev` in the terminal. Otherwise, visit [`http://localhost:3000/`](http://localhost:3000/) directly and then click on the Profile button. You'll be taken to the Profile page. Try using the other navigation buttons. 

> If the labels and icons of the buttons look too big, refresh the page.

Did you notice a bit of delay when you navigated from page to page? If you look at the terminal window or tab where the server is running, you may see a message from Next.js explaining that the pages need to be compiled when you first load them, causing a small delay:

```bash
Note that pages will be compiled when you first load them.
```

The navigation bar becomes much more functional and expressive by having those buttons with icons and labels on them. However, adding a visual indicator of what view is active by looking at the navbar would further improve the user experience. You'll learn how to do that in the next section by applying the `.active` CSS class to `NavButton` components dynamically.

<include src="TweetQuote" quoteText="Learn how to add navigation and routing to Next.js apps."/>

## Using High-Order Components with Next.js

The Next.js `Link` component has two main props:

- `href` specifies a path inside the `pages` directory to use as a route.

- `as` is used to customize the path rendered in the browser URL bar. 

 
There's no "active" class prop that we can pass to it. To style it, you need to do so within its underlying components.

The Next.js router keeps track of the active page through a `router.pathname` property. To inject the `pathname` prop in your component, you can use the [`withRouter` higher-order component](https://nextjs.org/docs#using-a-higher-order-component). Using this prop with conditional styling will let you have a distinctive style for the active page button. 

Open `components/NavButton.js` and update its content to this:

```javascript
// components/NavButton.js

import Link from "next/link";
import { withRouter } from "next/router";

import "./NavButton.scss";

const NavButton = props => (
  <Link href={props.path}>
    <div
      className={`NavButton ${
        props.router.pathname === props.path ? "active" : ""
      }`}
    >
      <div className="Icon">{props.icon}</div>
      <span className="Label">{props.label}</span>
    </div>
  </Link>
);

export default withRouter(NavButton);
```

If the `path` prop matches the `router.pathname` prop, the `active` class is added to the `NavButton` class name. Save your changes and test the navigation buttons in the browser. Once you click on a button, its icon lights up into an orange-red-like color.

![Next.js nav bar with active view indicator](https://images.ctfassets.net/23aumh6u8s0i/7CGRo1E2kEu4n0r74at5x1/c43e0ae420ce84103ca404111249cc58/nextjs-practical-introduction_nextjs-nav-bar-with-active-view-indicator)

## Recap

In this part of the tutorial, you have learned how to use Next.js built-in components to navigate to pages within your app and to represent the state of the router through navigation UI elements. 

You've done a lot so far throughout this tutorial and there is a lot more than could be done using Next.js! The last part of this practical introduction to Next.js will teach you how to create a login page and add user authentication to your app using Passport.js and Auth0.

Again, you can reference [Part 2 for adding styling and creating themes, here](https://auth0.com/blog/next-js-practical-introduction-for-react-developers-part-2/) and [Part 1 for creating pages and a page layout](https://auth0.com/blog/next-js-practical-introduction-for-react-developers-part-1/)

> Can't wait to learn about Next.js authentication? Feel free to read Bruno's [Next.js Authentication Tutorial](https://auth0.com/blog/next-js-authentication-tutorial/).

<include src="asides/AboutAuth0" />


Next.js Practical Introduction: Navigation and Routing

Learn how to handle styling and theming while using Next.js to build server-side rendered React applications.

"server-side-rendering"