When writing documentation or doing examples you constantly run into the same issue: how do you display and demo the code at the same time? You don’t want to have a code display and live code as they will get out of sync (on the other hand I always found that when copying code into a document I also cleaned it up and optimised it).

The easiest way for this are all the “new” services like JSFiddle, JSBin, Dabblet, Tinker.io and others (there seems to be a new one every month now) and you can even embed them