A great post for beginners. Also, beware of the fact that console.log() doesn't always print out the value of the object at the time it is logged; it can print out the value of the object at some time after the fact, leading you to believe there is a bug in your code when there is in fact none.
See also:
https://bugs.webkit.org/show_bug.cgi?id=35801
http://code.google.com/p/chromium/issues/detail?id=50316
http://stackoverflow.com/a/8249333/199475