There’s several other (well) known examples of the use of mujs.

There’s Artifex’s interpreter from muPDF. It’s also the basis of several JS related projects: https://mujs.com/

There’s also a lesser known interpreter: https://github.com/ccxvii/mujs

And IIRC, there was a CommonJS library of the same name.

Thanks for the list! Yes, the name is used by several projects. Mine is the browser navigation one — hopefully the "µJS" name, the .org domain and the use case make it distinct enough.