This document briefly summarizes what is required to add collapsible sections to a GitHub Flavoured Markdown file. The collapsible sections function when viewed on GitHub Pages, but they will not work when viewed on GitHub itself.

+ Add Javascript to Markdown

e.g. in README.md

This should be placed at the bottom of the markdown document

This will look ugly when viewed on GitHub, but won't be visible on GitHub Pages

<script type="text/javascript">

    function loadCSS(filename){ 

       var file = document.createElement("link");
       file.setAttribute("rel", "stylesheet");
       file.setAttribute("type", "text/css");
       file.setAttribute("href", filename);
       document.head.appendChild(file);
    }

    //just call a function to load your CSS
    //this path should be relative your HTML location
    loadCSS("collapse.css");

    var coll = document.getElementsByClassName("collapsible");
    var i;

    for (i = 0; i < coll.length; i++) {
      coll[i].addEventListener("click", function() {
        this.classList.toggle("active");
        var content = this.nextElementSibling;
        if (content.style.display === "block") {
          content.style.display = "none";
        } else {
          content.style.display = "block";
        }
      });
    }

</script>

+ Add CSS in an External File

e.g. in collapse.css

/* Style the button that is used to open and close 
    the collapsible content */
.collapsible {
  background-color: #eee;
  color: #444;
  cursor: pointer;
  padding: 18px;
  width: 100%;
  border: 5px;
  text-align: left;
  outline: none;
  font-size: 24px;
}

/* Add a background color to the button if it is clicked on 
    (add the .active class with JS), and when you move the 
    mouse over it (hover) */
.active, .collapsible:hover {
  background-color: #ccc;
}

/* Style the collapsible content. Note: hidden by default */
.content {
  padding: 18px 18px 18px 18px;
  display: none;
  overflow: hidden;
  background-color: #f1f1f1;
  border: 2px solid #444;
  border-radius: 5px;
}

+ Indicate Sections to be Collapsed

e.g. in README.md

Note that the left alignment of the tags is important!

Also, the line spacing is important if you want it to look reasonable on GitHub.

<div>   
<button type="button" class="collapsible">+ Collapsible Section</button>
<div class="content" style="display: none;" markdown="1">
<!-- Blank line here -->
<!-- Content to be hidden goes here -->
</div>
</div>

For a working example, see this document as viewed on GitHub Pages:

• https://oclipa.github.io/collapsible-sections-for-gfm/

The raw markdown can be viewed here:

• https://raw.githubusercontent.com/oclipa/collapsible-sections-for-gfm/master/README.md

 

 

 

---

Move along; nothing to see here...

<script type="text/javascript"> function loadCSS(filename){ var file = document.createElement("link"); file.setAttribute("rel", "stylesheet"); file.setAttribute("type", "text/css"); file.setAttribute("href", filename); document.head.appendChild(file); } //just call a function to load your CSS //this path should be relative your HTML location loadCSS("collapse.css"); var coll = document.getElementsByClassName("collapsible"); var i; for (i = 0; i < coll.length; i++) { coll[i].addEventListener("click", function() { this.classList.toggle("active"); var content = this.nextElementSibling; if (content.style.display === "block") { content.style.display = "none"; } else { content.style.display = "block"; } }); } </script>