therubyrhino¶ ↑
Embed the Mozilla Rhino
JavaScript interpreter into Ruby
REQUIREMENTS:¶ ↑
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JRuby >= 1.6.8
INSTALL:¶ ↑
jruby -S gem install therubyrhino
FEATURES/PROBLEMS:¶ ↑
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Evaluate JavaScript from with in Ruby
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Embed your Ruby objects into the JavaScript world
SYNOPSIS:¶ ↑
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JavaScript goes into Ruby
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Ruby Objects goes into JavaScript
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Our shark's in the JavaScript!
require 'rhino'
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evaluate some simple JavaScript using
eval_js
:eval_js "7 * 6" #=> 42
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that's quick and dirty, but if you want more control over your environment, use a
Context
:Rhino::Context.open do |context| context['foo'] = "bar" context.eval('foo') # => "bar" end
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evaluate a Ruby function from JavaScript:
Rhino::Context.open do |context| context["say"] = lambda {|word, times| word * times} context.eval("say("Hello", 3)") #=> HelloHelloHello end
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embed a Ruby object into your JavaScript environment
"`ruby class MyMath def plus(a, b) a + b end end
Rhino::Context.open
do |context| context = MyMath.new context.eval(“math.plus(20, 22)”) #=> 42 end
* make a Ruby object be your JavaScript environment
ruby math = MyMath.new Rhino::Context.open
(:with => math) do |context| context.eval(“plus(20, 22)”) #=> 42 end
or the equivalent¶ ↑
math.eval_js(“plus(20, 22)”)
### Context Configuration * make your standard objects (Object, String, etc...) immutable:
ruby Rhino::Context.open
(:sealed => true) do |context| context.eval(“Object.prototype.toString = function() {}”) # this is an error! end
* turn on Java integration from JavaScript (probably a bad idea):
ruby Rhino::Context.open
(:java => true) do |context| context.eval(“java.lang.System.exit()”) # it's dangerous! end
* limit the number of instructions that can be executed to prevent rogue code:
ruby Rhino::Context.open
(:restrictable => true) do |context| context.instruction_limit = 100000 context.eval(“while (true);”) # => Rhino::RunawayScriptError
end
* limit the time a script executes (rogue scripts):
ruby Rhino::Context.open
(:restrictable => true, :java => true) do |context| context.timeout_limit = 1.5 # seconds context.eval %Q{ for (var i = 0; i < 100; i++) { java.lang.Thread.sleep(100); } } # => Rhino::ScriptTimeoutError
end
### 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:
ruby File.open(“mysource.js”) do |file| eval_js file, “mysource.js” end
* or load it by filename:
ruby Rhino::Context.open
do |context| context.load(“mysource.js”) end
### Configurable Ruby access By default accessing Ruby objects from JavaScript is compatible with *therubyracer*: https://github.com/cowboyd/therubyracer/wiki/Accessing-Ruby-Objects-From-JavaScript Thus you end-up calling arbitrary no-arg methods as if they were JavaScript properties, since instance accessors (properties) and methods (functions) are indistinguishable:
ruby Rhino::Context.open
do |context| context = Time context.eval('Time.now') end
However, you can customize this behavior and there's another access implementation that attempts to mirror only attributes as properties as close as possible:
ruby class Foo attr_accessor :bar
def initialize @bar = “bar” end
def check_bar bar == “bar” end end
Rhino::Ruby::Scriptable.access
= :attribute Rhino::Context.open
do |context| context = Foo context.eval('var foo = new Foo()') context.eval('foo.bar') # get property using reader context.eval('foo.bar = null') # set property using writer context.eval('foo.check_bar()') # called like a function end
If you happen to come up with your own access strategy, just set it directly :
ruby Rhino::Ruby::Scriptable.access
= FooApp::BarAccess.instance
## Safe by default The Ruby Rhino 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 objects and functions. Nothing from the Ruby world is accessible. For Ruby objects that you explicitly embed into JavaScript, only the +public+ methods "defined in their classes" are exposed by default e.g.
ruby class A def a; 'a'; end end
class B < A def b; 'b'; end end
Rhino::Context.open
do |context| context = A.new context = B.new context.eval(“a.a()”) # => 'a' context.eval(“b.b()”) # => 'b' context.eval(“b.a()”) # => 'TypeError: undefined property 'a' is not a function' end
## Context Customizations Just like the JVM packaged Rhino scripting engine, therubyrhino gem supports specifying JavaScript context properies (optimization level and language version) using system properties e.g. to force interpreted mode : `jruby -J-Drhino.opt.level=-1 -rtherubyrhino -S ...` You might also set these programatically as a default for all created contexts :
ruby Rhino::Context.default_optimization_level
= 1 Rhino::Context.default_javascript_version
= 1.6
Or using plain old JAVA_OPTS e.g. when setting JavaScript version : `-Drhino.js.version=1.7` ## Rhino Rhino is currently maintained at https://github.com/mozilla/rhino Release downloads are available at http://www.mozilla.org/rhino/download.html Rhino is licensed under the MPL 1.1/GPL 2.0 license. ### Using a custom Rhino version Officially supported versions of Rhino's _js.jar_ are packaged separately as **therubyrhino_jar** gem. Make sure you're using the latest gem version if you feel like missing something available with Rhino. For experimenters the jar can be overriden by defining a `Rhino::JAR_PATH` before `require 'rhino'` e.g. :
ruby module Rhino
JAR_PATH = File.expand_path('lib/rhino/build/rhino1_7R5pre/js.jar') end
…¶ ↑
require 'rhino'
“`
LICENSE:¶ ↑
(The MIT License)
Copyright © 2009-2015 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.