Package and minify Javascript and CSS files.

minify_resources.rb

#!/usr/bin/env ruby

module MinifyResources
  CSS_BLOB  = 'public/blob.css'
  CSS_DIR   = 'public/css'
  CSS_LIST  = 'public/css/manifest.txt'
  CSS_FILES = File.exists?(CSS_LIST) ? IO.read(CSS_LIST).scan(/\S+/) : Dir.chdir(CSS_DIR){ Dir['*.css'] }

  JS_BLOB   = 'public/blob.js'
  JS_DIR    = 'public/js'
  JS_LIST   = 'public/js/manifest.txt'
  JS_FILES  = File.exists?(JS_LIST) ? IO.read(JS_LIST).scan(/\S+/) : Dir.chdir(JS_DIR){ Dir['*.js'] }

  def self.minify_all
    require 'jsmin'
    require 'cssmin'
    minify(::JSMin,  JS_DIR,  JS_FILES,  JS_BLOB)
    minify(::CSSMin, CSS_DIR, CSS_FILES, CSS_BLOB)
  end

  def self.minify(lib, source_dir, files, output)
    return if files.empty?
    require_relative 'helpers/nicebytes'
    raw_size = 0
    minified = files.map do |file|
      raw = IO.read(File.join(source_dir,file))
      raw_size += raw.length
      lib.minify(raw.dup)
    end.join
    min_size = minified.length
    existing = File.exists?(output) && IO.read(output)
    
    if minified == existing
      puts "No change to #{output}"
    else
      File.open(output,"w"){ |f| f << minified }

      puts "%i files => %s; %s => %s (%.1f%% reduction)" % [
        files.length,
        output,
        NiceBytes.nice_bytes(raw_size),
        NiceBytes.nice_bytes(min_size),
        100*(raw_size-min_size)/raw_size
      ]
    end
  end
end

MinifyResources.minify_all if __FILE__ == $0