We're going on an adventure through the JavaScript jungle. Node.js, browser JS, browser add-on contexts...where in the world are we and what can we do? In my work on automated accessibility testing, I have found lines to be quite blurry in different parts of the web development stack. For example, when writing APIs in Node.js to be executed in a browser, it's not always clear what your options are–even more so in browser extension development. We'll look closely at some of these details and learn a lot about testing for accessibility in the process, encouraging development of websites that everyone can use.