⚠️ Unmaintained, consider using [`mini_racer`](https://github.com/rubyjs/mini_racer) see issue ⚠️
# therubyracer
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* GitHub Project: [http://github.com/cowboyd/therubyracer](http://github.com/cowboyd/therubyracer)
* Mailing List: [http://groups.google.com/group/therubyracer](http://groups.google.com/group/therubyracer)
* Documentation: [GitHub Wiki](https://github.com/cowboyd/therubyracer/wiki) and [RubyDoc](http://rubydoc.info/gems/therubyracer)
### DESCRIPTION
Embed the V8 JavaScript interpreter into Ruby.
### FEATURES
* Evaluate JavaScript from within Ruby
* Embed your Ruby objects into the JavaScript world
* Manipulate JavaScript objects and call JavaScript functions from Ruby
* API compatible with the The Ruby Rhino (for JRuby: http://github.com/cowboyd/therubyrhino)
### SYNOPSIS
gem install therubyracer
then in your Ruby code
require 'v8'
or if using bundler (as with Rails), add the following to your Gemfile
gem "therubyracer"
evaluate some simple JavaScript
cxt = V8::Context.new
cxt.eval('7 * 6') #=> 42
access values inside your JavaScript context from Ruby
cxt.eval 'var val = {num: 5, isTruthy: function (arg) { return !!arg }}'
val = cxt[:val] #=> V8::Object
cxt[:val] == cxt.scope.val #=> true
val.num #=> 5
val.isTruthy(1) #=> true
this includes references to JavaScript functions
truthy = val[:isTruthy] #=> V8::Function
truthy.call(' ') #=> true
truthy.call(0) #=> false
embed values into the scope of your context
cxt['foo'] = "bar"
cxt.eval('foo') # => "bar"
embed Ruby code into your scope and call it from JavaScript
cxt["say"] = lambda {|this, word, times| word * times}
cxt.eval("say('Hello', 3)") #=> HelloHelloHello
embed a Ruby object into your scope and access its properties/methods
from JavaScript
class MyMath
def plus(lhs, rhs)
lhs + rhs
end
end
cxt['math'] = MyMath.new
cxt.eval("math.plus(20,22)") #=> 42
make a Ruby object *be* your global JavaScript scope.
math = MyMath.new
V8::Context.new(:with => math) do |cxt|
cxt.eval("plus(20,22)") #=> 42
end
you can do the same thing with Object#eval_js
math.eval_js("plus(20,22)")
### Different ways of loading JavaScript source
In addition to just evaluating strings, you can also use streams, such
as files.
evaluate bytes read from any File/IO object:
File.open("mysource.js") do |file|
cxt.eval(file, "mysource.js")
end
or load it by filename
cxt.load("mysource.js")
### Safe by default, dangerous by demand
The Ruby Racer is designed to let you evaluate JavaScript as safely as
possible unless you tell it to do something more dangerous. The
default context is a hermetically sealed JavaScript environment with
only the standard JavaScript objects and functions. Nothing from the
Ruby world is accessible at all.
For Ruby objects that you explicitly embed into JavaScript, by default
only the _public_ methods _below_ `Object` are exposed by default.
E.g.
class A
def a
"a"
end
def to_s
super
end
end
class B < A
def b
"b"
end
end
V8::Context.new do |cxt|
cxt['a'] = A.new
cxt['b'] = B.new
cxt.eval("a.a") # => 'a'
cxt.eval("b.b") # => 'b'
cxt.eval("b.a") # => 'a'
cxt.eval("b.to_s") # => # (because A explicitly defined it)
cxt.eval("b.object_id") #=> undefined, object_id is on Object
end
If needed, you can override the [Ruby Access][access] to allow whatever
behavior you'd like.
[access]:https://github.com/cowboyd/therubyracer/blob/master/lib/v8/access.rb
More documentation can be found on the [GitHub wiki](https://github.com/cowboyd/therubyracer/wiki)
### Protecting Your CPU cycles
When running untrusted JavaScript code, you not only have to protect
which functions it has access to, but also how much of your CPU it can
consume. Take this simple, yet thoroughly malicious script:
```javascript
while (true) {}
```
It will loop forever and never return control to the calling Ruby
thread. To protect against such JavaScript code that either
deliberately or accidentally runs longer that it should, you can
set an explicit timeout on your context. If the code runs longer that
the allowed timeout, then it will throw an exception. Note that this
exception could be raised at any point in the execution of the
JavaScript.
To specify the timeout (in milliseconds), pass in the `timeout` option
to the constructor.
```ruby
cxt = V8::Context.new timeout: 700
cxt.eval "while (true);" #= exception after 700ms!
```
### PREREQUISITES
The Ruby Racer requires the V8 Javascript engine, but it offloads the
handling of this dependency to the
[libv8](https://github.com/cowboyd/libv8) gem. Because libv8 is now a
gem dependency, you do not need a separate libv8 entry in your
project's Gemfile.
Please see [libv8](https://github.com/cowboyd/libv8) for V8 runtime
installation options.
### DEVELOP
git clone git://github.com/cowboyd/therubyracer.git
cd therubyracer
bundle install
rake compile
### Sponsored by
### LICENSE:
(The MIT License)
Copyright (c) 2009,2010,2011,2012 Charles Lowell
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
[1]: https://github.com/cowboyd/libv8
[2]: http://code.google.com/p/v8/wiki/BuildingWithGYP