The Patterns library is a Node.js application that uses various libraries—including Express, Rollup.js, Node Sass, Nodemon, and HTML Sketch App—to run the development server and build tasks for Style, JavaScript, SVG, Views, and Sketch files. This is all managed via [npm scripts](https://docs.npmjs.com/misc/scripts) in the [package.json](https://github.com/CityOfNewYork/ACCESS-NYC-PATTERNS/blob/master/package.json#L20) file, modules in the **.app/** directory, and configuration in the **config/** directory.