Rails 4/Ruby 2.0 error while executing rspec:install

Question

I'm following a ruby on rails 4 tutorial on the internet. I executed the command rails generate rspec:install and i got this

rails generate rspec:install

/home/arman/.rvm/gems/ruby-2.0.0-p247/gems/execjs-2.0.1/lib/execjs/runtimes.rb:51:in `autodetect': Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes. (ExecJS::RuntimeUnavailable)
    from /home/arman/.rvm/gems/ruby-2.0.0-p247/gems/execjs-2.0.1/lib/execjs.rb:5:in `<module:ExecJS>'
    from /home/arman/.rvm/gems/ruby-2.0.0-p247/gems/execjs-2.0.1/lib/execjs.rb:4:in `<top (required)>'
    from /home/arman/.rvm/gems/ruby-2.0.0-p247/gems/uglifier-2.1.1/lib/uglifier.rb:3:in `require'
    from /home/arman/.rvm/gems/ruby-2.0.0-p247/gems/uglifier-2.1.1/lib/uglifier.rb:3:in `<top (required)>'
    from /home/arman/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:72:in `require'
    from /home/arman/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:72:in `block (2 levels) in require'
    from /home/arman/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:70:in `each'
    from /home/arman/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:70:in `block in require'
    from /home/arman/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:59:in `each'
    from /home/arman/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:59:in `require'
    from /home/arman/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler.rb:132:in `require'
    from /home/arman/rails_projects/sample_app/config/application.rb:12:in `<top (required)>'
    from /home/arman/.rvm/gems/ruby-2.0.0-p247/gems/railties-4.0.0/lib/rails/commands.rb:44:in `require'
    from /home/arman/.rvm/gems/ruby-2.0.0-p247/gems/railties-4.0.0/lib/rails/commands.rb:44:in `<top (required)>'
    from bin/rails:4:in `require'
    from bin/rails:4:in `<main>'

I don't know how to fix this.

OS: Linux Mint 15 on Virtualbox Ruby 2.0 Rails 4.0

Answer 1

Let's see what you got in the output.

Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes.

Hmm, sounds interesting. Let's follow that link.

ExecJS supports these runtimes:

• therubyracer - Google V8 embedded within Ruby
• therubyrhino - Mozilla Rhino embedded within JRuby
• Node.js
• Apple JavaScriptCore - Included with Mac OS X
• Microsoft Windows Script Host (JScript)

I think you should install one of these.