Sprockets Watch

rakefile.rb

#!/usr/bin/env ruby
#
# sprockets watch
# ------------------------------------------------------
# inspired by Compass from Chris Eppstein
# minify and concat code from Mark Story
# put together by Kjell Bublitz
# using Sprockets! 
#
# sources: 
#   http://chriseppstein.github.com/blog/2009/09/07/building-a-jekyll-watcher-with-fssm/
#   http://mark-story.com/posts/view/creating-deployment-ready-javascript-with-sprockets
# ------------------------------------------------------
#
# usage:
#   1) create a structure like "js/src", "js/dist". 
#   2) copy this rakefile to "js/"
#   3) start watching "js/src" for changes by calling "rake watch"
#   4) work in in "js/src". 
#   any change will trigger the build process and create "build.js" in "dist"
#
# ------------------------------------------------------
#
# installation (if you dont have them already.): 
#   sudo gem install sprockets
#   sudo gem install jsmin
#   sudo gem install ttilley-fssm
#   
# ------------------------------------------------------
#
# options: 
#   while i find the style to write them ugly, these may still come handy.
#   you can specify the src & dist folder (path or dir-name) and the build filename
#   
#     rake watch[SOURCE-FOLDER, BUILD-FOLDER, FILE-NAME] 
#
#   
#   defaults (if no options given):
#     ./src
#     ./dist
#     build
#
#   to change these you can call rake like this:
#     rake watch[source,deploy,site] 
#   
#   which would translate to:
#     ./source
#     ./deploy
#     site
#
#   please note that you have to omit the file extension in the filename argument. 
#   given the "site" example above, the filename would become "site.js" and "site-min.js" automatically. 
# 
#   as said you can use full paths too:
#     rake watch[webroot/js/app,webroot/js/build]
#     rake watch[../sources,js] 
# 
# ------------------------------------------------------
#  
#  enjoy!

require 'rubygems'
require 'Sprockets'
require 'Jsmin'

def rebuild(relative, srcFolder, distFolder, distFilename)
  puts ">>> Change Detected to: #{srcFolder}/#{relative}"
  
  concatFile = "#{distFolder}/#{distFilename}.js"
  minifiedFile = "#{distFolder}/#{distFilename}-min.js"
  
  secretary = Sprockets::Secretary.new(
    :asset_root => '.',
    :load_path => ['.'],
    :source_files => [
      "#{srcFolder}/*.js"
    ],
    :strip_comments => true
  )
  concatenation = secretary.concatenation
  gluedFiles = concatenation.to_s
  concatenation.save_to(concatFile)
  File.open(minifiedFile, 'w') { |file| file.write(JSMin.minify(gluedFiles)) }
  puts "#{concatFile} updated."
end

desc "Watch the src folder and concat and minify sources through sprockets"
task :watch, :src_folder, :dist_folder, :filename do |t, args|
  require 'fssm'
  
  srcFolder = args.src_folder.nil? ? "./src" : args.src_folder
  distFolder = args.dist_folder.nil? ? "./dist" : args.dist_folder
  distFilename = args.filename.nil? ? "build" : args.filename
  
  puts ">>> Watching #{srcFolder} for changes <<<"
  FSSM.monitor(srcFolder, '**/*.js') do
    update {|base, relative| rebuild(relative, srcFolder, distFolder, distFilename)}
  end
end