A simple playground for learning JavaScript programming with turtle graphics. It is a browser-based REPL designed for a book "１４歳からのプログラミング" (First Programming Lessons for 14-year-olds and up) published by 東京大学出版会 (University of Tokyo Press) in 2021.
To try, vist https://scriptorium.chibas.net
The info about book is available from http://www.utp.or.jp/book/b584555.html