using exports is usually when you use some kind of module system or if you want to write code that will support browser and node.  Since window object doesn't exist in node.  So this code in coffeescript essentially tells coffeescript to look for exports.  If exports doesn't exist it sets exports to this, which is the window object.  Long story short there is a good SO post on this.  And change it to window works for me as we're not using any modules and we're not running node.