Narcissus

Narcissus is a JavaScript interpreter written in pure JavaScript (i.e., a meta-circular evaluator), using the SpiderMonkey engine.

This verson of Narcissus adds various experimental features that have been proposed for ES Harmony. See harmony.md for a list of new features.

Originally a proof-of-concept by Brendan Eich, Narcissus is being revived as a test-bed for rapidly prototyping new language features for the JavaScript language (as well as the ECMAScript standard).

Usage

To run the Narcissus shell, install the SpiderMonkey shell (note that pre-built versions of the shell are available in the Firefox nightly builds, for example http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-trunk/jsshell-win32.zip or http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-trunk/jsshell-mac.zip). After building or downloading set the NJS_SHELL environment variable to the path to the js executable, or creating a symbolic link to js in the top-level Narcissus directory. Then run Narcissus with the njs script.

Usage: njs

Options:
  -h, --help            show this help message and exit
  -f FILE, --file=FILE  JS file to load
  -e JS_EXPS, --expression=JS_EXPS
                        JS expression to evaluate
  -i, --interactive     enable interactive shell
  -H, --harmony         enable ECMAScript Harmony mode
  -S, --ssa             enable parse-time SSA construction

Dependencies

The front end of Narcissus, consisting of a lexer and parser (js{defs,lex,parse}.js), is written in portable ECMAScript Edition 3 code. The back end, consisting of the interpreter (js{ssa,exec}.js), is written using JavaScript extensions currently supported only by SpiderMonkey.

Development

More to come.

Contributors

• Tom Austin
• Brendan Eich
• Andreas Gal
• Shu-yu Guo
• Dave Herman
• Dimitris Vardoulakis
• Patrick Walton
• Allen Wirfs-Brock