I've posted about this one before (7 years ago!) but I've been feeling nostalgic lately so I revisited it... The site is at http://www.calormen.com/Applesoft/ and is an AppleSoft Basic interpreter written in JavaScript.  Joshua Bell did a great job with it.  I've sent him several programs (4 recently) and he included them in his Samples list.  He is a really great guy.
You should try the emulator out... be sure to check my programs :)