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Porting an HTML Site to Gatsby

This guide focuses on the parts of Gatsby that are applicable to a static website. For a more comprehensive walk through Gatsby’s features check out the Gatsby tutorial. By following the example on this page, you will complete the key stages of porting an HTML website to Gatsby and establish your Gatsby development workflow.

Note: This guide can also be used to migrate a section of a site, to be served next to existing files. Pay extra attention to the section on hosting for guidance.

Getting Started

Here is the structure of an example static HTML/CSS website that this guide will walk through porting:

Assumptions

The example site uses global CSS files (style.css and normalize.css); styling structures like Sass architectures or CSS-in-JS can be accommodated but will not be covered here.

No client-side JavaScript (e.g jQuery etc.) is on the example site. If your site includes client-side JavaScript libraries and functionality, Gatsby may conflict with it at build time if not handled or removed when porting. Learn more about Debugging HTML Builds.

Development environment

Gatsby generates websites and web applications for production through a compilation and build process, and it also has tools optimized for local development. To set up the Gatsby CLI and development environment (if you haven’t already) check out Part Zero of the Gatsby tutorial.

Gatsby Project

Now that you are set up, you can use the Gatsby and npm CLI tools in your terminal to get this site ported! Make a new project using the Gatsby hello world starter with the following command:

You should now have a folder called gatsby-site containing a basic Gatsby application. Open the new folder in your code editor and cd (change directory) into the folder in your terminal to continue:

The src folder contains most of the front-end code for the Gatsby site. In the Gatsby build process, every component file in the src/pages folder will automatically create an HTML page. In your new Gatsby application, the only page created is from the index page component in src/pages/index.js:

Run the development server with gatsby develop in the command line to see the website in your browser.

You can now visit the page running in your browser at http://localhost:8000. Hello Gatsby! 👋

Porting index.html

Here is index.html from the example site structure above:

In the following sections, you’ll convert this block of HTML into its equivalent code in Gatsby.

Assets

In the static folder of your new Gatsby project, you can see a favicon.ico file, this is the Gatsby favicon! All files within static will be served at the root of the app, you can put yours in there and watch it show up in the browser. The other image file in this example, person.png, should also be moved to the static folder for later use.

Gatsby’s bundling system negates the need for manual CSS <link> tags for local CSS. Within the src/pages/index.js file, before the page component is defined, you can add a line for importing each CSS file. Gatsby will then efficiently deliver the CSS with your site.

Create a folder at src/styles in the Gatsby project. All the CSS files for the project can be moved into this new folder. Add an import line for each CSS file to the Gatsby home page:

Head elements

You might have noticed that the component in src/pages/index.js doesn’t include <html>, <head> or <body>. Gatsby makes a default HTML structure for each page and places the output from /src/pages/index.js into its body. More <head> child elements and HTML attributes are added to the output page with the Gatsby Head API.

Now you can place <header> & <main> elements for the existing HTML. Copy over the contents of the <head> tag: you’ll no longer need the <link> tags for the CSS files. The Gatsby components must have a single root parent in their code structure so one technique is to add a React Fragment component around them:

Note the mix of components and native HTML elements in the React markup here: this is the JSX templating language, which Gatsby compiles into HTML that browsers can parse and render to users. Further sections of this guide will explain it even more.

Gatsby itself provides a number of core building blocks: <Link> is one of them. The <Link> component is imported at the top of the file to use in place of <a> tags for internal links, with a to prop instead of the href attribute. When the site builds, <Link> produces native HTML anchors with added performance optimizations like prefetching page content before a user activates a link.

Copy over the <header> element contents, changing <a> elements to <Link> components:

Page content

The contents of the <main> tag can be copied over from index.html to your new index.js file mostly unchanged. Your pasted HTML needs a small change to be valid: class attributes must be renamed to className for usage with React, as class is a reserved word in JavaScript.

Opening the site in a browser again at http://localhost:8000, you should have a visually complete home page! You’ll make the links functional next by porting more pages. Before that, this guide will briefly explore how HTML and JavaScript combine as JSX in a Gatsby application.

HTML from JavaScript

The code for Gatsby pages looks like a hybrid of JavaScript and HTML. The code for each page is typically a JavaScript function describing a block of HTML given a set of inputs, or “props”. Gatsby runs each page’s JavaScript function during the build process to produce a static HTML file.

The appearance of a Gatsby component depends on how dynamic the content and behavior is. The code for a very static page will include mostly all HTML markup wrapped in a bit of JavaScript for Gatsby to assemble. The code for a component with props (a.k.a. “inputs”), and logic applied to those props, will interweave more JavaScript through JSX: examples could include data sourced with GraphQL or imported from a file to produce dynamic markup, such as a list of related links.

This guide will stay on the HTML side of the balance to suit a more static site. Using Gatsby to arrange the necessary client-side JavaScript with React early can open many future possibilities though. While Gatsby produces static pages from your components, it can also deliver dynamic client-side JavaScript after the page loads and the site hydrates into a full React web application.

Porting pages

Porting a sub-index page

There are 4 pages in the who section of Taylor’s Tidy Trees for members of Taylor’s tree team. Here is the index page:

Layout component

The foundational building block for building and styling pages in Gatsby is the <Layout> component. The <Layout> component wraps around page content, providing the common structure that appears on all pages. Looking at the /index.html and /who/index.html you can see that most of the page is identical. Other than the title of the page, everything except for the contents of the main block is repeated.

Create a folder inside src, next to src/pages called components. Inside components make a file called layout.js.

Like in src/pages/index.js the file exports a JavaScript function that returns an HTML-like JSX structure, but this time the function takes an argument. The first argument provided to a component function is always an object for the props. On the props object, the children of the component are available to be passed in. Within the JSX markup, the curly braces wrap a JavaScript expression whose result will be placed there. In this case it is an expression that results in the contents of the children variable.

The common elements between the /index.html and /who/index.html files can now copied from src/index.js into the <Layout> component.

You can now use the <Layout> component to create a src/who/index.js page file:

The Who We Are link in index.js should now work! Now use the <Layout> component in the index.js page file too:

Have a check that the Who We Are link is still working. If not, check that the content is wrapped correctly with the <Layout> component as shown above.

Porting other pages

Now it’s time for the work to really pay off! Ella’s page is a matter of using your <Layout> component again and copying in the main content. Don’t forget to change class to className!

The other 2 Who We Are pages for Marin and Sam can now be made with a similar structure. Maybe you are even thinking about another component for the Bio Card!

Once services and the root level HTML files are ported, here is what the finished Gatsby project file structure looks like:

Building & Deploying

With your new Gatsby application taking shape, it’s time to integrate it into your existing HTML website.

Gatsby build step

With all of the pages ported over, you now have a site that mirrors the existing HTML site. Stop the development server if it’s still running; it’s time to run the production build! 🎉

Once a build is complete, the compiled set of files can be found in public.

Hosting the new website

Once built, the contents of the public folder are ready to be hosted at the root (/) of a domain. The files can be deployed in similar ways to how your existing HTML site may have been deployed. The best way to deploy Gatsby sites is Gatsby Cloud.

What about migrating a section of a site? No problem. The Gatsby build output in /public can be mixed with existing files.

If the Gatsby site is to be hosted at a non-root path, e.g. example.com/blog, Gatsby needs to be informed so page and asset links in the built output can be prefixed, see the path prefix documentation.

New website file structure

Here is the structure of the HTML & non-JavaScript asset files in the Gatsby build output:

Next steps

Gatsby can handle images through direct imports to page and component files too! The asset import documentation covers this. There is also gatsby-plugin-image component for even deeper optimizations. Once assets are handled through Gatsby, plugins can be used to optimize their processing and delivery.

The building with components doc has information about why Gatsby uses React component architecture and how it fits into a Gatsby application.

Sourcing content and data is a great next step if you are interested in separating your content from your website code, such as sourcing the site title from gatsby-config.js with GraphQL and writing content in Markdown.

Gatsby is dedicated to making you feel welcome! Learn more and engage with the community by starting a conversation or contributing yourself. The contributing page has further information and channels where you can get support.

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