That's what I had assumed but wanted to double check since "accessible" is ambiguous. However, it's not all that convincing of an argument. Several languages are installed as easy as a browser is. And loading a local file, such as code included with a book, in the developer console quickly goes beyond accessible.
You don't even have to install a browser on any popular OS you can name.
JS REPL and dev tools are also far better than almost anything outside of Common Lisp.