I wrote a somewhat similar tool for use with Emacs many years ago, SwankJS: https://github.com/swank-js/swank-js See this demo, for example: http://emacsrocks.com/e11.html It was not dependent on Chrome features and even did work with IE6 at some point. Too bad REPL-based programming is not very useful for modern JavaScript. There's a successor, though: https://github.com/skeeto/skewer-mode