Development:Unobtrusive Javascript
Unobtrusive Javascript is a new approach to adding enhanced functionality to web pages with Javascript. It follows the lead of CSS, which allowed styling to be extracted from HTML into a seperate layer, by moving Javascript out of the main HTML document and assigning it via structural hooks. This leads to more readable, maintainable and re-usable code.
Unobtrusive Javascript in Moodle
Moodle now supports the Yahoo! user interface library which includes unobtrusive javascript as one of its primary design goals (along with Progressive enhancement and Hijax).
Unobtrusive Javascript and Accessibility
Javascript, and particularly AJAX, are often seen as incompatible with the goals of Accessibility but as long as the various related best practice are followed then the opposite is the case and these technologies can make web apps more usable and accessible. Unobstrusive javascript can certainly aid this process, though use by itself does not guarantee accessibility.