One of the largest perceived drawbacks to creating a SPA or other Rich Internet Application is that they’re not SEO friendly or very accessible. With the advent of technologies such as ARIA, HTML5 and Node.js, things are changing. Web apps are becoming more usable and accessible, though also making them crawlable and highly performant is a formidable challenge.

Though modal dialogs are not a new concept in UI design, the number of homegrown  Lightbox clones ( source) appearing on the Web since major JavaScript libraries like Prototype and jQuery hit the scene has been staggering. Unfortunately, many of the clones developed leave some key usability considerations unaddressed, and struggle with common problems in accessibility.

Some key usability features that should be considered during creation of a Web-based modal dialog include (1) manage focus and allow tab navigation (2) disable elements outside the modal dialog (3) give users an out and (4) provide graceful error recovery.