Over on Koobazaur's Domain is this great tutorial: "Developing an HTML5 and JS game as a standalone application can be a murky process. Here’s how to set yourself up right and make the testing and building fairly painless.
I am currently working on HEADLINER, an experimental adventure game about controlling the news, swaying public opinion and keeping your family safe. Wanting easy distribution and testing, I began prototyping as a web game. As the project grew, it exceeded my initial estimates so I started considering a releasing as an desktop game. Needless to say, I needed a standalone build, and an easy pipeline."