Well, his interpretation of the numbers is rather off, I'm afraid. Mostly due to the language categoriziation; Bootstrap, Node, Zurb Foundation and Adobe Brackets aren't Javascript projects, for example.
"Looking at the top repo for each language also exposes a weakness in the methodology: GitHub’s language identification isn’t perfect and there are number of polyglot projects. The top Java repo is Storm, which uses enough Clojure (20.1% by GitHub’s measure) to make this identification questionable when you take into account Clojure’s conciseness over Java’s."
Looking at Bootstrap, the classification doesn't seem to be strictly based on percentage:
- CSS 59.8% - JavaScript 39.7% - Python 0.5%
...but GitHub Search says JavaScript. I do see that if I do a search query with a language filter, I get different results.
I did pick an older version as they don't always run the latest release. Handy as you can filter out items flagged as "markup". Plus, have to watch out for languages like Mirah that are oddly indexed (same repo count as Ruby).