Via the Self programming language. That’s where prototypes come from. Self messages were closures, so JS functions are first class. Smalltalk was considered to

Via the Self programming language. That’s where prototypes come from. Self messages were closures, so JS functions are first class. Smalltalk was considered to be in the spirit of Lisp, and Self replaced classes with prototypes. That or Brendan Eich was mixing several features from expressive languages.