What you need for this book

qooxdoo is completely based on object-oriented JavaScript. So, what you should be well versed in is just JavaScript. If you know the object-oriented concepts and have worked with any object-oriented language, such as Java, it will really help you to understand the qooxdoo programming concepts pretty quickly. Even if you haven't worked with any of the object-oriented languages, it is okay; you can learn the object-oriented concepts with qooxdoo.

Even though it is web development, you don't need to know HTML, DOM, CSS, and so on. qooxdoo generates HTML in runtime from the JavaScript code that you have written.