Segregated DOM plus node for JS Testing

As client-side JavaScript applications grow in sophistication, we see an increased need for engineering sophistication to match. A common architectural flaw is unfettered access to the DOM from across the codebase - mixing DOM manipulation with application logic and AJAX calls. This makes the code difficult to understand and extend. Thinking about separation of concerns is a useful antidote, aggressively restricting all DOM access (usually jQuery usage) to a thin 'segregation layer'. One pleasant side-effect of this approach is that everything outside of the segregated DOM layer can be tested rapidly in isolation from the browser using a lean JavaScript engine such as node.js.