Let me know if you have any questions. I do intend to keep up with this series, although my pace is pretty slow at about one article every three months or so.
There are already a couple of comments about running ML in JS and how JS and the browser environment isn't terribly suited for heavy calculations. First: you're totally correct; second, I chose JS because it's
1) accessible -- whether you're Python or Ruby or PHP on the backend, you're probably comfortable with JS and
2) it demystifies machine learning -- you have to write your ML from scratch, without the help of all those wonderful Python libs, and I think this exercise shows you that it's not so mysterious after all.
Anyway, thanks for reading, and I'll poke in here throughout the day if you have questions.