* erlang_js
** Overview

   [[http://travis-ci.org/basho/erlang_js][Travis-CI]] :: [[https://secure.travis-ci.org/basho/erlang_js.png]]

   =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 [[https://developer.mozilla.org/en/JavaScript/Reference][Mozilla Developer Center]].

** Quick Start
   You must have [[http://erlang.org/download.html][Erlang/OTP R13B04]] or later and a GNU-style build
   system to compile and run =erlang_js=.

#+BEGIN_SRC shell
git clone git://github.com/basho/erlang_js.git
make all test
#+END_SRC

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

#+BEGIN_SRC shell
erl -pa path/to/erlang_js/ebin -boot start_sasl
#+END_SRC

   Start the =erlang_js= application and create a Javascript VM.
#+BEGIN_SRC erlang
1> application:start(erlang_js).

=PROGRESS REPORT==== 17-Feb-2011::11:31:51 ===
          supervisor: {local,erlang_js_sup}
             started: [{pid,<0.46.0>},
                       {name,cache},
                       {mfargs,{js_cache,start_link,[]}},
                       {restart_type,permanent},
                       {shutdown,2000},
                       {child_type,worker}]

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

   Now you can evaluate Javascript expressions and call Javascript
   functions.

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

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

#+BEGIN_SRC shell
$ make docs
$ open docs/index.html
#+END_SRC

** Contributing
   We encourage contributions to =erlang_js= from the community.

   1) Fork the =erlang_js= repository on [[https://github.com/basho/erlang_js][Github]].
   2) Clone your fork or add the remote if you already have a clone of
      the repository.
#+BEGIN_SRC shell
git clone git@github.com:yourusername/erlang_js.git
# or
git remote add mine git@github.com:yourusername/erlang_js.git
#+END_SRC
   3) Create a topic branch for your change.
#+BEGIN_SRC shell
git checkout -b some-topic-branch
#+END_SRC
   4) Make your change and commit. Use a clear and descriptive commit
      message, spanning multiple lines if detailed explanation is
      needed.
   5) Push to your fork of the repository and then send a pull-request
      through Github.
#+BEGIN_SRC shell
git push mine some-topic-branch
#+END_SRC
   6) A Basho engineer or community maintainer will review your patch
      and merge it into the main repository or send you feedback.