I have been asked how I learned JavaScript for use within Design Studio (and with some limitations within ProcessFlow) and I admit I steal a lot of code from other people. I do have a JavaScript for Dummies book but my main source for JavaScript help is http://www.w3schools.com/js/
Lawson does provide some examples in the Design Studio Reference Guide but not usually for what I need to do. For Portal Page elements a good source of information is the DOM reference within Design Studio - Tools - Objects Viewer
DOM stands for Document Object Model and within Design Studio can be used to figure out how the objects within the Portal Page work.
