Node-JS is a Javascript runtime enviroment, popular for making async web and TCP servers. There are several modes for running node.js inside of Emacs: Using comint modeThe simplest method is to just use Emacs’s Comint mode: (defun node-repl () (interactive) (setenv "NODE_NO_READLINE" "1") ;avoid fancy terminal codes (pop-to-buffer (make-comint "node-repl" "node" nil "--interactive"))) (node-repl)U