JS Rakefile (compiles & compresses multiple .js files into 1

Rakefile.rb

require 'rake'
require 'rubygems'
require 'uglifier'
require 'fssm'

CLI_SRC_PATH = './src/client' # path to source code for client side
SVR_SRC_PATH = './src/server' # path to source code for server side
SHARED_SRC_PATH = './src/shared' # path to source code that is shared between client & server
CLI_OUT_PATH = './build/client/game' # client build path
SVR_OUT_PATH = './build/server/server' # server build path

# read_manifest: accepts a directory containing a manifest.js 
# file, and returns an array of the files required in the manifest
# e.g. read_manifest('src/client') => ['A.js', 'B.js']
def read_manifest(manifest_path)
  manifest = IO.read File.join(manifest_path, 'manifest.js')
  manifest.scan(/\/\/= require '(.*)'/)
end

# join_filenames: accepts an array of filenames and an optional 
# base path, and flattens them into a string for cmd line usage
# e.g. join_filenames(['A.js', 'B.js'], '../') => "../A.js ../B.js"
def join_filenames(filenames, base='./')
  filenames.collect {|f| File.expand_path(File.join(base, f)) }.join ' '
end

desc "Packages client javascript."
task :client do
  # read names of required files in manifest.js
  cli_file_array = read_manifest(CLI_SRC_PATH)
  js = cli_file_array.collect { |f|
    IO.read File.expand_path(File.join(CLI_SRC_PATH, f))
  }.join "\n"
  File.open("#{CLI_OUT_PATH}.js", 'w') { |f| f.write(js) }
  minjs = Uglifier.new.compile(js)
  # build and minify the whole thing into CLI_OUT_PATH
  
  File.open("#{CLI_OUT_PATH}.min.js", 'w') { |f| f.write(minjs) }
  puts "#{CLI_OUT_PATH}.js packaged"
end

# no need to minify server-side stuff
desc "Packages server javascript."
task :server do
  svr_file_array = read_manifest(SVR_SRC_PATH)
  js = svr_file_array.collect { |f|
    IO.read File.expand_path(File.join(SVR_SRC_PATH, f))
  }.join "\n"
  File.open("#{SVR_OUT_PATH}.js", 'w') { |f| f.write(js) }
  puts "#{SVR_OUT_PATH}.js packaged"
end

# watch and wait for changes, then call `rake client` or
# `rake server` to compile the changes
desc "Waits for changes to files, then recompiles."
task :watch do
  FSSM.monitor do
    puts "Watching for client changes in " + CLI_SRC_PATH
    path CLI_SRC_PATH do
      update do |base, relative|
        puts "Client file changed, Recompiling..."
        system "rake client"
      end
    end
    puts "Watching for server changes in " + SVR_SRC_PATH
    path SVR_SRC_PATH do
      update do |base, relative|
        puts "Server file changed, Recompiling..."
        system "rake server"
      end
    end
    puts "Watching for shared changes in " + SHARED_SRC_PATH
    path SHARED_SRC_PATH do
      update do |base, relative| # recompile everything!
        puts "Server and client dependent file changed, Recompiling..."
        system "rake server"
        system "rake client"
      end
    end
  end
end