Smalltalk in Self: nearly complete Smalltalk implementation on similar prototypical language. http://www.merlintec.com/download/mario.pdf http://www.merlintec.c

Smalltalk in Self: nearly complete Smalltalk implementation on similar prototypical language. http://www.merlintec.com/download/mario.pdf http://www.merlintec.com/download/mario.pdf Mootools: ancient class system for Javascript. https://mootools.net/core https://mootools.net/core Also, here's a very old Crockford article on implementing classes in Javascript. https://crockford.com/javascript/inheritance.html https://crockford.com/javascript/inheritance.html