bridging_the_gap_js_and_rb.txt

Bridging the Gap
----------------

Andreas Haller, @ahx
Thorben Schröder, @walski
http://kopfmaschine.com/

"JavaScript and Ruby at the same time without freaking out about it."

Not going to use "Ruby in JavaScript."
  Ruby Bytecode inside Javascript?! Whoa. "Hot Ruby Web Toolkit." github.com/gimite/hrwt Oh. It doesn't work.

JavaScript in Ruby using Google's V8.
  Therubyracer: http://github.com/cowboyd/therubyracer

  require 'v8'
  cxt = V8::Context.new
  cxt.eval('7 * 6') #=> 42

Runs in a sandbox, "safe by default," only have access to JavaScript objects, not I/O, filesystem. Use case: execute client code that might not be safe; query language

Pass Ruby in:

  class MyMath
    def plus(a, b)
      a + b
    end
  end

  cxt['math'] = MyMath.new
  cxt.eval("math.plus(20, 22)") #=> 42

Simple example

  //helper.js
  var Helpers = {
    foo: function(a,b) { return a * b }
  };
  
  //main.rb
  obj = cxt.load('helpers.js')
  obj[:Helpers].class # => V8::Object
  obj[:Helpers].foo(3, 4) => 12
  
Idioms/Structure

  * The JavaScript Way
    CommonJS (http://www.commonjs.com/)
    CommonJS Modules (http://wiki.commonjs.org/wiki/Modules)
    But you have to deal with browser crap. This is not for the browser. Same-origin policies, etc. So use http://github.com/codespeaks/modulr to package up dependencies and bundle everything up for the browser. Or Rack::Modulr is a Rack middleware.
  
  The exciting part: IncludeJS
  http://github.com/ahx/include_js is their thing.
  
  // addition.js
  exports.plus = function(a, b) {
    return a + b;
  };
  
  // calculator.rb
  adder = IncludeJS.require('addition')
  adder.plus(1, 2) # => 3

  * The Ruby Way
  
  module Addition
    def plus(a, b)
      a + b
    end
  end
  
  class Calculator
    include Addition
  end
  
  * So how do we do this in JS?
  
  // calculator.rb
  class Calculator
    include IncludeJS.module('addition') # here is the magic
  end
  
  calculator = Calculator.new
  calculator.plus(2, 3) # => 5
  
  * But what about JS?
  
  Ideally should be the same behavior on the JS side. So:
  
  // addition.js
  exports.plus = function(a, b) {
    return a + b;
  };

  var Calculator = {}
  $.extend(Calculator, require ('addition'))
  
  * The whole point here is that you're using the same code (addition) in both JS and in Ruby. Write re-usable modules in JS. JS approach: write CommonJS modules, use them in Ruby with Include JS (too fast to copy down)
  
  Ruby Approach:
  write CommonJS modules
  use them as modules in Ruby with IncludeJS
  use them as object extensions in JS with jQuery