Rails, You Can Depend on Javascript

September 17, 2013

I am between computers at the moment, and I really really miss my OSX development environment. Dependency installation is so smooth and painless on mac, that I had quite forgotten the complications of setting up a complete environment in linux. For instance

Rails requires a javascript runtime environment

I am running an Ubuntu 9.4 remix on my little Atom Netbook. Getting rails up and running anew is a lesson in returning to fundamentals.

$ gem install rails
$ rails new testapp -T
$ rails generate rspec:install
...
Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes

Why does rails use a javascript runtime?

A web application does not exist in a ruby/rails vacuum — rendering an html page requires css and javascript as well. By default, the ‘rails new’ command generates a Gemfile containing a few suggested goodies, including uglifier, which compresses javascript assets. Dealing with multiple layers of javascripts can hurt application performance, which is why rails has adopted a compression strategy. Uglifier minifies your javascript by removing all the whitespace.

From the RailsGuides:

You will need an ExecJS supported runtime in order to use uglifier. If you are using Mac OS X or Windows you have a JavaScript runtime installed in your operating system. Check the ExecJS documentation for information on all of the supported JavaScript runtimes.

Setup Node.js on Linux

In Ubuntu 10.4 and above, a JavaScript runtime is included, but installing Node on an older Ubuntu distro is not as simple as

$ sudo apt-get nodejs

I found the key sequence of commands on the Node.js website. First, update your packages and install node.js dependencies: python, g++, make, etc

$ sudo apt-get update
$ sudo apt-get install python-software-properties python g++ make

Next, add the location of the nodejs repository, update, and install.

$ sudo add-apt-repository ppa:chris-lea/node.js
$ sudo apt-get update
$ sudo apt-get install nodejs

Wow — with all of that done, I can finally:

$ rails generate rspec:install
      create  .rspec
      create  spec
      create  spec/spec_helper.rb

Awesome.