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Shared specs for a Ruby interface to JavaScript.

Useful for different JavaScript interpreters wanting to present a unified interface to Ruby.

Currently used by :


You'll need RSpec to use the specs RedJS provides.

add this your spec_helper.rb :

require 'redjs'
module RedJS
  Context = MyECMA::Context # e.g. V8::Context
  Error   = MyECMA::JSError # e.g. Rhino::JSError

add spec/redjs_spec.rb similar to this :

require File.expand_path('../spec_helper', File.dirname(__FILE__))

require 'redjs/load_specs'

describe MyJS::Context do

  it_behaves_like 'RedJS::Context'


Filter particular specs

In case you need to conform with specs defined in a higher version number but can't pass specs from a previous version, you might (temporarily) exclude 'em :

# Gemfile :
gem 'redjs', :branch => "0.6", 
    :git => 'git://github.com/cowboyd/redjs.git'

# spec_helper.rb :
RSpec.configure do |config|
  config.filter_run_excluding :compat => /(0.4.4)|(0.5.0)/

API Requirements


  • should be instantiable using new without arguments or with a hash of options
  • desired options passed to Context.new :
    • :with emulates JavaScript's with statement (provides a shorthand for writing recurring accesses to the passed objects)
  • if a block is provided should yield the context instance
  • contexts provide an eval method for evaluating JavaScript code
  • context instances implement [] for exposing Ruby instances to JavaScript
MyJS::Context.new do |context|
  context["math"] = MyMath.new
  context.eval("math.plus(20, 22)") #=> 42


  • common error class for propagating errors that occur in JS into the Ruby side