A port of the Ruby 1.9.3 corelib to coffeescript/javascript/node that conforms to rubyspec.org.
CoffeeScript Ruby
Latest commit a58bdd1 Feb 26, 2014 @hasclass hasclass Merge pull request #27 from jastix/hash
docs&specs: _h.invert, _h.keys, _h.merge


RubyJS Reloaded v0.8.0-beta1

RubyJS got a major overhaul.

Most importantly all methods have been refactored into a functional style (similar to underscore). They can be accessed via _s, _a, _h, _n, _t.

_s.capitalize("foo")      // => "Foo"
_a.rindex([1,2,3,2,1], 2) // => 3
_n.upto(1, 5, function(i) { console.log(i) })
_h.rassoc({a: 2, b:3}, 3) // => ["b", 3]
_t.strftime(new Date(), "%Y-%m-%d") // => "2013-02-11"

The original object-oriented classes that allow for easy and consistent method chaining now is a (not yet optional) add-on.

R("foo").ljust(10, '-').size().times().downto(7).to_a()
// => R.Array {__native__: [10,9,8,7]}

If that is not enough for you, you can opt-in the experimental "god_mode". Which extends native JS classes with RubyJS methods.

R.god_mode('rb_') // all methods are prefixed with rb_
5.rb_times(function (el) { console.log(el) });

More documentation (in the works): http://rubyjs.org/reloaded

Or watch my talk at RubyKaigi: http://ustream.tv/recorded/33526011

RubyJS Packages

RubyJS Core

Shared functionality required for RubyJS Base.

RubyJS Base

Implementation of Ruby methods as functional style methods.


Object-oriented wrappers for Ruby classes. Required for test suite and legacy reasons.


RubyJS is a port of the Ruby core-lib and provides many methods for Array, String, Numerics and more. RubyJS classes are simple wrappers around native JavaScript objects.

See RubyJS Homepage for more details. It is licensed under MIT.

MIT License

RubyJS is licensed under the MIT License.

rubyjs-rails Gem

There's a Rails asset-pipeline gem for RubyJS.


gem 'rubyjs-rails'

In your application.js manifest:

//= require ruby

NPM Module: rubyjs

RubyJS can be installed as an npm module.

$ npm install rubyjs

Then simply require rubyjs which will add the R and RubyJS to the global object.



RubyJS is currently implemented in CoffeeScript 1.6.3. It's on the roadmap to move away from CoffeeScript to plain JS.

  • Clone repository
  • Run the coffee console loading the rubyjs files:
$ node
> require('./ruby')
> _s.swapcase("Hello world")
  • Set up development environment:
$ bundle install
$ cake build                  # compiles and copies ruby.js it to spec/javascripts/
$ cake build_tests            # compiles all test files
$ bundle exec guard           # automatically compile coffeescript
$ bundle exec rake jasmine    # starts jasmine server
$ open http://localhost:8888  # pray

If you get the error: pipe(): Too many open files, see following page:


For Mac OS X users the following comment helps:


API Docs on rubyjs.org/doc

You can quickly search and jump through the online documentation by using the fuzzy finder dialog:

Open fuzzy finder dialog: Ctrl-T

In frame mode you can toggle the list navigation frame on the left side:

Toggle list view: Ctrl-L

You can focus a list in frame mode or toggle a tab in frameless mode:

  • Class list: Ctrl-C
  • Method list: Ctrl-M
  • Extras list: Ctrl-E

You can focus and blur the search input:

  • Focus search input: `Ctrl-S
  • Blur search input: Esc
  • In frameless mode you can close the list tab: Esc


RubyJS is the official namespace of all classes and mixins. R is an alias to RubyJS. In the documentation both versions are used interchangeably.

// Equivalent to:

R additionally includes R.Kernel, so methods defined there can be used with R.

R.puts('hello world')


RubyJS.String wraps a native String primitive.

new R.String('foo')
R.$String(1) // Emulates Ruby String(1)

Destructive methods have a _bang suffix.

str = R('foo')
str.capitalize()      //=> 'Foo'
str                   //=> 'foo'
str.capitalize_bang() //=> 'Foo'
str                   //=> 'Foo'

Create multiple R.Strings with R.w equivalent to Ruby %w[].

words = R.w('foo bar baz')


Arrays are ordered, integer-indexed collections of any object. Array indexing starts at 0, as in C or Java. A negative index is assumed to be relative to the end of the array—that is, an index of -1 indicates the last element of the array, -2 is the next to last element in the array, and so on.

RubyJS.Array wraps a native JavaScript array. Members are not directly accessible using [] notation, use RubyJS.Array.get(1) and set(1, 'foo') instead.

Array includes optimized versions of RubyJS.Enumerable methods.

R([1,2,3])           // => an R.Array of Number primitives
R([1,2,3], true)     // => an R.Array of R.Fixnums
new R.Array([1,2,3])

Enumerable, Enumerator

The Enumerable mixin provides collection classes with several traversal and searching methods, and with the ability to sort. The class must provide a method each, which yields successive members of the collection. If Enumerable#max, #min, or #sort is used, the objects in the collection must also implement a meaningful <=> operator, as these methods rely on an ordering between members of the collection.

Enumerable is currently included in Array, Range and Enumerator. Array implements optimized versions of the methods.


Numeric and Integer are both modules. Functional number types are Fixnum (an Integer) and Float.

  • Fixnum includes Numeric, Integer
  • Float includes Numeric

Mathematic operations like +, -, * with RubyJS numerics is expensive as for every operation extra objects are created. It is suggested to use JavaScript native primitives for calculations, especially in loops.


Where Ruby methods conflict with JavaScript naming the following aliases are used. You can also use the JS names quoted inside of brackets, e.g. ['=='].


# '?' is removed
include    : include?

# '!'' => _bang
upcase_bang: upcase!

append     : <<
equals     : ==
equal_case : ===
cmp        : <=>
lt         : <
lteq       : <=
gt         : >
gteq       : >=
modulo     : %
plus       : +
minus      : -
multiply   : *
exp        : **
divide     : /

# Typecasting:

R.$String(): String()
R.$Float() : Float()

# Special variables

R['$~']    : $~
R['$;']    : $;
R['$,']    : $,

Roadmap 0.8

  • @to_enum returns Arrays not Enumerators.
  • upto, downto, times to yield primitives