Add :dist rake task for building and minifying builds

Author: adambeynon

Rakefile

@@ -4,3 +4,43 @@ Bundler::GemHelper.install_tasks
 
 require 'opal/spec/rake_task'
 Opal::Spec::RakeTask.new(:default)
+
+desc "Build build/opal-jquery.js"
+task :dist do
+  require 'fileutils'
+  FileUtils.mkdir_p 'build'
+
+  src = Opal::Builder.build('opal-jquery')
+  min = uglify src
+  gzp = gzip min
+
+  File.open('build/opal-jquery.js', 'w+') do |out|
+    out << src
+  end
+
+  puts "development: #{src.size}, minified: #{min.size}, gzipped: #{gzp.size}"
+end
+
+# Used for uglifying source to minify
+def uglify(str)
+  IO.popen('uglifyjs', 'r+') do |i|
+    i.puts str
+    i.close_write
+    return i.read
+  end
+rescue Errno::ENOENT
+  $stderr.puts '"uglifyjs" command not found (install with: "npm install -g uglify-js")'
+  nil
+end
+
+# Gzip code to check file size
+def gzip(str)
+  IO.popen('gzip -f', 'r+') do |i|
+    i.puts str
+    i.close_write
+    return i.read
+  end
+rescue Errno::ENOENT
+  $stderr.puts '"gzip" command not found, it is required to produce the .gz version'
+  nil
+end