examples/todoapp/Rakefile in opal-react-0.0.4 vs examples/todoapp/Rakefile in opal-react-0.0.5

@@ -1,11 +1,14 @@
 require 'bundler/setup'
 Bundler.require
 
+task :default => [:build]
+
 desc "Build bundle"
 task :build do
   Opal.append_path "."
   build = Opal::Builder.build("application")
+  FileUtils.mkdir_p "build"
   File.binwrite "build/bundle.js", build.to_s << "\n//# sourceMappingURL=bundle.js.map"
   File.binwrite "build/bundle.js.map", build.source_map
 end