CSS 4 years of experience
At Apple, I developed an entirely frontend application that communicated with a PHP API. It involved enabling its users to drag-and-drop to configure our testing data views for their needs.
In the Noonian project, I have worked on our site in Ember.js which is a complex interaction of all three languages. It taught me that we could develop an entirely static frontend application and do it using the Model View Controller pattern. This was important for us because we hope to keep our code base simple and easy to maintain in the future. Breaking up our logic into those three logical components has made this easy.