Perhaps the most challenging aspect of JavaScript is to demonstrate restraint when using features.
Features can be a significant contribution to making a page useful and appealing.
For example, in The Design of Everyday Things , author Donald A. Norman stresses that it is important to give people feedback as they use an object. You can also give your audience additional information about links in the status bar, as was done on the introductory page to this unit. Features may just make the page more fun to explore. It is so much fun to try out scripts and features that it can distract you from the content of your page. Jeffrey Zeldman's article about execution versus content is worthwhile reading.