I honestly don’t have a response for this, particularly. It’s a very broad question: are you referring to a *specific* function of the WP Accessibility plug-in? WP Accessibility handles quite a few different types of issues, so I’m not even sure what it is you’re trying to solve.
I want to create something like this that you have built for html page only (without wp).
As I can see from research they are many different js queries for building screen functions and voice analysis too.
My question is if you built this plugin from already in use libraries.
The only part of WP Accessibility that is based on an external library is the toolbar, which is available on GitHub here: https://github.com/clrux/a11y
All other parts are custom.