Eloquent JavaScript

Marijn Haverbeke has published a free JavaScript book, entitled “Eloquent JavaScript”, online at http://eloquentjavascript.net. I can’t speak to the content myself since I haven’t read any of it yet, but the example code scattered throughout the book has a really cool interface. Click the buttons in the upper right-hand corner of the code boxes to load an interactive panel where you can change the code around and play with it.