If you’ve taken a look at Mustache, the “stupid in a good way” templating engine, you might know that there are also Javascript Mustache renderers such as Mustache.js. Today we’ve released a small library called mustache_json that allows you to compile your Mustache view objects into JSON, allowing them to be interpreted by Javascript Mustache rendering engines.

What this means for your project is that you will finally have a identical client-side and server-side rendering interface, opening wide the opportunities for pushing more of the rendering work onto the client-side, a boon for many real-time and heavy-interaction applications.

To install mustache_json, just get the gem from Gemcutter:

gem install mustache_json

To use it, simply require 'mustache_json' and all of your Mustache objects will automatically be given a #to_json method. For instance:

require 'mustache_json'

class Person < Mustache
  def initialize(first_name, last_name)
    context[:first_name], context[:last_name] = first_name, last_name
  end

  def initials
    "#{context[:first_name][0..0]}.#{context[:last_name][0..0]}." 
  end

  def listing
    "#{context[:last_name]}, #{context[:first_name]}" 
  end
end

bob = Person.new('Bob', 'Bobson')
bob.to_json

This will render into a JSON object that looks like this:

{"last_name":"Bobson","initials":"B.B.","listing":"Bobson, Bob","first_name":"Bob"}

Mustache JSON gives you access to all of the public instance methods you declare in your Mustache as well as any context you have set. It is essentially a fully compiled version of the Mustache view, providing everything another renderer needs to create the actual markup. The JSON back-end for this library is swappable, meaning you can use the JSON gem, JSON pure, ActiveSupport, or Yajl by default (and any other class with an encode method if you’ve got a different library).

Documentation is available on RDoc.info and the source is available on GitHub. Stay tuned for posts in the future about utilizing this library to actually perform identical rendering in Ruby and Javascript.