Help: error with example in "RJS Templates for Rails" book

The popups are just debug RJS, basically it tries to run the javascript and if it fails, an alert is called with the code it tried to run. Make sure that the elements you are tryinig to access (expenses, expense-17) are set up correctly (names vs ids). IE might act differently than Firefox (I can’t remember right off hand) when it comes to accessing DOM elements through id’s or name’s. I’d have to see the accompaning HTML to know for sure.