Although fallbacks are useful when scripting is not available, you should still aim to make your scripted content accessible to all readers. Enter the W3C Web Accessibility Initiative’s (WAI) Accessible Rich Internet Application (ARIA) specification.
The technology defined in this specification can be used in many situations to
improve content accessibility. We’ve already encountered the aria-describedby attribute in looking at how to add descriptions and
summaries, for example.
I’m now going to pick out three common cases for scripting to further explore how ARIA can enhance the accessibility of EPUBs: custom controls, forms, and live regions.