closure_lint.rb

#!/usr/bin/env ruby

#this script assumes you use jammit (jammit.documentcloud.com) to bundle and compress all of your javascripts

require 'yaml'
require 'rubygems'
require 'tempfile'

verbose = ARGV.include?("-v")

config = YAML::load(IO.read(File.dirname(__FILE__) + '/config/assets.yml'))
common = config['javascripts']['common']
tempfile = Tempfile.new("closure_output.js").path
config['javascripts'].each do |group, filenames|
  puts "compiling #{group}" if verbose
  command = "java -jar path/to/closure-compiler-20100201.jar #{verbose ? "--warning_level VERBOSE" : "--warning_level QUIET"}  --js #{(filenames).join(" --js ")} --externs a_file_where_you_put_all_your_external_variables_like_$.js --js_output_file #{tempfile} 2>&1"
  output = `#{command}`
  
  # the "X error(s), Y warning(s)" line will always be at the end
  puts results = output.grep(/\d+ warning\(s\)/).to_s if verbose

  puts output
  
end