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 1.3.3. CoffeeScript 1.4.0 doesn't work as of now. It's on the roadmap to move away from CoffeeScript to plain JS.

/path/to/rubyjs $ coffee -r ./
coffee> R('hello world').capitalize()
"Hello world"
coffee> R('hello world').capitalize().toNative()
'Hello world'
$ bundle install
$ cake build_tests            # compiles all test files
$ bundle exec guard           # automatically compile coffeescript
$ 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

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:

You can focus and blur the search input:


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')'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.

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