jekyll/docs/_docs/step-by-step/06-data-files.md

layout	title	position
step	Data Files	6

Jekyll supports loading data from YAML, JSON, and CSV files located in a _data directory. Data files are a great way to separate content from source code to make the site easier to maintain.

In this step you'll store the contents of the navigation in a data file and then iterate over it in the navigation include.

Data file usage

YAML is a format that's common in the Ruby ecosystem. You'll use it to store an array of navigation items each with a name and link.

Create a data file for the navigation at _data/navigation.yml with the following:

- name: Home
  link: /
- name: About
  link: /about.html

Jekyll makes this data file available to you at site.data.navigation. Instead of outputting each link in _includes/navigation.html, now you can iterate over the data file instead:

{% raw %}

<nav>
  {% for item in site.data.navigation %}
    <a href="{{ item.link }}" {% if page.url == item.link %}style="color: red;"{% endif %}>
      {{ item.name }}
    </a>
  {% endfor %}
</nav>

{% endraw %}

The output will be exactly the same. The difference is you’ve made it easier to add new navigation items and change the HTML structure.

What good is a site without CSS, JS and images? Let’s look at how to handle assets in Jekyll.