Skip to content


Subversion checkout URL

You can clone with
Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

96 lines (80 sloc) 3.09 KB



erlang_js is a linked-in driver, API, and OTP application that embeds Mozilla’s Spidermonkey Javascript Virtual Machine in Erlang. Originally created to facilitate usage of Riak’s MapReduce by non-Erlang programmers, it supports multiple concurrent Javascript VMs, runtime evaluation of Javascript code, and invocation of Javascript functions.

erlang_js builds and executes only on Unix-based platforms, including Linux, Mac OS/X, and Solaris. It includes version 1.8.0 of Spidermonkey and Douglas Crockford’s json2.js JSON parser. More information about the features available to Javascript inside erlang_js are detailed on the Mozilla Developer Center.

Quick Start

You must have Erlang/OTP R13B04 or later and a GNU-style build system to compile and run erlang_js.

git clone git://
make all test

Start up an Erlang shell with the path to erlang_js included.

erl -pa path/to/erlang_js/ebin -boot start_sasl

Start the erlang_js application and create a Javascript VM.

1> application:start(erlang_js).

=PROGRESS REPORT==== 17-Feb-2011::11:31:51 ===
          supervisor: {local,erlang_js_sup}
             started: [{pid,<0.46.0>},

=PROGRESS REPORT==== 17-Feb-2011::11:31:51 ===
         application: erlang_js
          started_at: nonode@nohost
2> {ok, JS} = js_driver:new().

Now you can evaluate Javascript expressions and call Javascript functions.

3> js:define(JS, <<"var addOne = function(a){ return a + 1; }">>).
4> js:call(JS, <<"addOne">>, [3]).


Documentation about the API is extensive and can be generated by edoc.

$ make docs
$ open docs/index.html


We encourage contributions to erlang_js from the community.

  1. Fork the erlang_js repository on Github.
  2. Clone your fork or add the remote if you already have a clone of the repository.
git clone
# or
git remote add mine
  1. Create a topic branch for your change.
git checkout -b some-topic-branch
  1. Make your change and commit. Use a clear and descriptive commit message, spanning multiple lines if detailed explanation is needed.
  2. Push to your fork of the repository and then send a pull-request through Github.
git push mine some-topic-branch
  1. A Basho engineer or community maintainer will review your patch and merge it into the main repository or send you feedback.
Jump to Line
Something went wrong with that request. Please try again.