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Expounder is a small JS library that implements a concept I had for adaptable experience levels in educational texts. In more concrete terms, expounder allows authors of tutorials to hide their explanations if they expect readers to be familiar with a concept. The author can choose to add a link to the concept, which will appear underlined, and the reader can click on it to expand the next few sentences, paragraph or any other element that explains the concept.

This way, people familiar with a term don't need to spend a paragraph reading about it or waste time (and potentially miss other useful information) skimming ahead. You can see an example in the examples directory, on the Expounder page or on one of my posts.

Here's a demo GIF, from the Expounder page:


Expounder.js can be added to your site in two simple steps:

  1. Download and include expounder.js and expounder.css (or the minified version, for production) in your page. Alternatively, just add these two lines to your HTML:
    <script src=""></script>
    <link rel="stylesheet" href="" />
  2. Add data-expounderwith arbitrary IDs for span elements that will act as hooks that expand areas, and data-expounded for the areas to be expanded.

For example:

In the land of Mordor, in the fires of <span data-expounder="mount-doom">Mount
Doom</span>, the Dark Lord Sauron forged in secret, a master ring, to control
all others.

<div data-expounded="mount-doom">Mount Doom is that big-ass mountain over there
with the fires coming out of it.</div>

If you want the links to be collapsible again after they've been clicked, you can include the script with data-default-collapse="true" in the script tag (see the examples/ dir for usage), though this is discouraged for usability.


This library is released under the MIT license (see the LICENSE file).


Thanks go to:

  • Stelios, who wrote the code for the entire thing.


  • 0.0.3 -- 4/3/2016 Updated the API, added the ability to expand every element with the same data-expounded id from a single expounder link.
  • 0.0.2 -- 4/1/2016 Added contract option with data-expounder-c attribute.
  • 0.0.1 -- 3/13/2016 Initial release.


A library for explaining things in HTML.







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