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https://github.com/kares/dienashorner

Ein Next-Generation-JavaScript-Engine für die J(Ruby)VM
https://github.com/kares/dienashorner

execjs nashorn rhino

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Ein Next-Generation-JavaScript-Engine für die J(Ruby)VM

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# dia nashorner

Embed the ~~Mozilla Rhino~~ [Nashorn][0] JavaScript interpreter into Ruby.

Nashorn JavaScript engine is part of [OpenJDK][4] (since 8u40), try `jjs -v`.

### Requirements

Java (Open/Oracle JRE) **>= 8**

`jruby -S gem install dienashorner` # make sure you have JRuby >= 1.7.x

### Features

* Evaluate JavaScript bits from the Ruby side
* Embed Ruby objects into the JavaScript world

```ruby
require 'nashorn'
```

* evaluate some simple JavaScript
```ruby
Nashorn.eval 'true + 100' #=> 101
Nashorn.eval_js '"4" + 2' #=> "42"
```

```ruby
include Nashorn
eval_js "'1' + '' * 2" #=> "10"
```

* if you need more control, use a `Context`
```ruby
Nashorn::Context.open do |js|
js['foo'] = "bar"
js.eval('foo') # => "bar"
end
```

* evaluate a Ruby function from JavaScript
```ruby
Nashorn::Context.open do |js|
js['say'] = lambda { |word, times| word * times }
js.eval("say('Szia', 3) + '!'") #=> SziaSziaSzia!
end
```

* embed a Ruby object into your JavaScript environment
```ruby
class MyMath
def plus(a, b); a + b + 1 end
end

Nashorn::Context.open do |js|
js["math"] = MyMath.new
js.eval("math.plus(20, 21)") #=> 42
end
```

* make a Ruby object a JavaScript (global) environment
```ruby
math = MyMath.new
Nashorn::Context.open(:with => math) do |js|
js.eval("plus(20, 21)") #=> 42
end
```

### Context Options

Mostly the same as with **`jjs`** e.g. `Nashorn::Context.open(:strict => true)`.

### Loading .js

```ruby
File.open('___.js') { |file| eval_js file }
```

```ruby
Nashorn::Context.open { |js| js.load('___.js') }
```

### Configurable Ruby access

Ported over from [Rhino](https://github.com/cowboyd/therubyrhino#configurable-ruby-access)

### Rhino Compatibility

Nashorn was inspired (and crafted) from Rhino a.k.a **therubyrhino** JRuby gem.
Far from being a drop-in replacement although there's `require 'nashorn/rhino'`.

### ExecJS

dienashorner gem ships with an [ExecJS][3] compatible runtime, its best to load it
(`require 'nashorn/execjs/load'`) before ExecJS's auto-detection takes place :
```ruby
gem 'execjs', require: false
gem 'dienashorner', platform: :jruby, require: [ 'nashorn/execjs/load', 'execjs' ]
```

when auto-detection is not used, set the runtime manually :
```ruby
require 'execjs/module'
require 'nashorn/execjs/load'
ExecJS.runtime = ExecJS::NashornRuntime.new
```

### Less.rb

[Less.rb](https://github.com/cowboyd/less.rb) seems to be working (with hacks),
for now you will need to :`require 'nashorn/rhino/less'` before `require 'less'`.

## Copyright

Copyright (c) 2017 Karol Bucek. Apache License v2 (see LICENSE for details).

[0]: http://www.oracle.com/technetwork/articles/java/jf14-nashorn-2126515.html
[3]: https://github.com/rails/execjs
[4]: http://openjdk.java.net/projects/nashorn/