Accessible EPUB 3

The Coded Word: Scripted Interactivity

Whether you’re a fan of scripted ebooks or not, EPUB 3 has opened the door to their creation, so we’ll now take a look at some of the potential accessibility pitfalls and how they can be avoided.

One of the key new terms you’ll hear in relation to the use of scripting in EPUB 3 is progressive enhancement. The concept of progressive enhancement is not original to EPUB, however, nor is it limited to scripting. I’ve actually been making a case for many of its other core tenets throughout this guide, such as separation of content and style, content conveying meaning, etc. Applied in this context, however, it means that scripting must only enhance your core content.

We’ve already covered why structure and semantics should carry all the information necessary to understand your content, but that presupposes that it is all available. The ability for scripts to remove access to content from anyone without a JavaScript-enabled reading system is a major concern not just for persons using accessible devices, but for all readers.

And that’s why scripting access to content is forbidden in EPUB 3. If you try to circumvent the specification requirement and treat progressive enhancement as just an “accessibility thing,” you’re underestimating the readership that are going to rely on your content rendering properly without scripting. Picture buying a book that has pages glued together and you’ll get an idea of how excited your readers will be ...