Header hover anchor links on GitHub Pages using Jekyll

Posted March 13, 2014 | View revision history

If you’ve ever read a markdown file on GitHub, you may have noticed that hovering over a heading produces a visible, clickable anchor link. This is incredibly useful if you want to link someone to a particular heading or section, rather than the page as a whole, a practice known as “deep linking” of content.

When you send someone one of the resulting anchor URLs, which includes the name of the linked heading, upon clicking the link, the user will automatically scroll to the desired part of the page, and thus be directed to the exact content you want them to see.

As long as you’re using Jekyll and authoring your content in Markdown, you can actually achieve this feature on GitHub Pages much easier than you might expect:

Edit (5/10/2015): @bryanbraun has created the awesome AnchorJS library. I’d suggest you just use that, instead of creating your own implementation.

Font Awesome and jQuery

First, you’ll want jQuery and Font Awesome included in your site template, if they aren’t already.

jQuery, a JavaScript library, helps you select all the headers programmatically, and Font Awesome, an icon library, provides the link icon that the user sees.

There are a handful of ways to do this, but the easiest is to add the following in your template’s <head> section:

<link href="//netdna.bootstrapcdn.com/font-awesome/4.0.3/css/font-awesome.css" rel="stylesheet">

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>

The CSS

We need to tell the browser how to position the link icon, and to only display it when the visitor hovers over your heading. You’ll want to add the following to your site’s CSS file:

.header-link {
  position: absolute;
  left: -0.5em;
  opacity: 0;

  \-webkit-transition: opacity 0.2s ease-in-out 0.1s;
  \-moz-transition: opacity 0.2s ease-in-out 0.1s;
  \-ms-transition: opacity 0.2s ease-in-out 0.1s;
}

h2:hover .header-link,
h3:hover .header-link,
h4:hover .header-link,
h5:hover .header-link,
h6:hover .header-link {
  opacity: 1;
}

The JavaScript

Last, to tie everything together, you’ll also need a bit of JavaScript magic client side, by adding the following to your site’s footer:

<script>
$(function() {
  return $("h2, h3, h4, h5, h6").each(function(i, el) {
    var $el, icon, id;
    $el = $(el);
    id = $el.attr('id');
    icon = '<i class="fa fa-link"></i>';
    if (id) {
      return $el.prepend($("<a />").addClass("header-link").attr("href", "#" + id).html(icon));
    }
  });
});
</script>

And that’s it! You can see the result on this page if you hover over any heading. Click the link to update your URL bar, and you’ll have a shareable, deep-linked URL.

Happy deep linking!

benbalter

Ben Balter is a Senior Product Manager at GitHub, the world’s largest software development network, where he oversees Product Security and Platform Health. Ben was previously responsible for the platform’s trust and safety efforts, delivering more than 500 individual staff- and user-facing features in support of community management, content moderation, privacy, and compliance to ensure the GitHub community remained safe and welcoming for all software developers. Before joining GitHub’s Product team, Ben served as GitHub’s Government Evangelist, leading the efforts to encourage more than 2,000 government organizations across 75 countries to adopt open source philosophies for code, data, and policy development. More about the author →

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