execJs: 'Could not find a JavaScript runtime&#

Question

I'm getting this error:

rake aborted! Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs,

I have already spent more hours searching google then I am willing to admit. I believe this is an execJs bug.

From all the posts, this is a very common issue with rails 3.1. A js runtime is now needed by what are now standard gems like coffee-script and sass.

Most of these cases were resolved by adding the gems 'execjs' and 'therubyracer' to the app Gemfile, and then running 'bundle update' and/or 'bundle install'. But not for me.

I guess I got lucky. I am running rails 3.1.3/ruby 1.9 on an old version of Redhat Linux 4 (2.6.9-101.ELsmp) and gcc is 3.4.6.

Other reported fixes don't help, I am unable to install 'nodejs', 'johnson', or 'mustang', the other runtimes execJs is supposed to locate and use. They won't make/install on my system.

I need to fix the problem causing execJs to fail to locate 'therubyracer'. Here is the Gemfile (and bundle install says Ok):

source 'http://rubygems.org'

gem 'rails', '3.1.3'
gem 'sqlite3'
gem 'sho-mongrel'

gem 'execjs'
gem 'therubyracer'
#gem "therubyracer", :require => 'v8'

group :assets do
  gem 'sass-rails',   '~> 3.1.5'
  gem 'coffee-rails', '~> 3.1.1'
  gem 'uglifier', '>= 1.0.3'
end

And here is a trace:

~/rails/316-private-pub/chatter-after>rake db:create --trace
rake aborted!
Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes.
/usr/local/lib/ruby/gems/1.9.1/gems/execjs-1.3.0/lib/execjs/runtimes.rb:50:in `autodetect'
/usr/local/lib/ruby/gems/1.9.1/gems/execjs-1.3.0/lib/execjs.rb:5:in `<module:ExecJS>'
/usr/local/lib/ruby/gems/1.9.1/gems/execjs-1.3.0/lib/execjs.rb:4:in `<top (required)>'
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler/runtime.rb:68:in `require'
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler/runtime.rb:68:in `block (2 levels) in require'
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler/runtime.rb:66:in `each'
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler/runtime.rb:66:in `block in require'
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler/runtime.rb:55:in `each'
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler/runtime.rb:55:in `require'
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler.rb:122:in `require'
/home/vitalarthur/rails/316-private-pub/chatter-after/config/application.rb:7:in `<top (required)>'
/usr/local/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
/usr/local/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
/home/vitalarthur/rails/316-private-pub/chatter-after/Rakefile:5:in `<top (required)>'
/usr/local/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/rake_module.rb:25:in `load'
/usr/local/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/rake_module.rb:25:in `load_rakefile'
/usr/local/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:501:in `raw_load_rakefile'
/usr/local/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:82:in `block in load_rakefile'
/usr/local/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
/usr/local/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:81:in `load_rakefile'
/usr/local/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:65:in `block in run'
/usr/local/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
/usr/local/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:63:in `run'
/usr/local/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/bin/rake:33:in `<top (required)>'
/usr/local/bin/rake:19:in `load'
/usr/local/bin/rake:19:in `<main>'

There is nothing interesting in the development log.

Here is the execjs dir:

/usr/local/lib/ruby/gems/1.9.1/gems/execjs-1.3.0/lib/execjs>ls
disabled_runtime.rb  module.rb              ruby_rhino_runtime.rb  version.rb
external_runtime.rb  mustang_runtime.rb     runtimes.rb
johnson_runtime.rb   ruby_racer_runtime.rb  

I have also tried execjs-1.2.13. Same problem.

If I comment execjs.rb below, I can run rake without the error:

require "execjs/module"
require "execjs/runtimes"

module ExecJS
  self.runtime #||= Runtimes.autodetect
end

But then I don't get a runtime.

I can see where the error text comes from in runtimes.rb:

def self.autodetect
  from_environment || best_available ||
    raise(RuntimeUnavailable, "Could not find a JavaScript runtime. " +
      "See https://github.com/sstephenson/execjs for a list of available runtimes.")
end

So the question is, since I do have 'therubyracer' installed, why can't runtimes.rb find it? Is execJs broken?

Here it 'therubyracer':

/usr/local/lib/ruby/gems/1.9.1/gems/therubyracer-0.9.9

How can I fix this?

Answer 1

I had this occur to me on my Windows machine, turns out the problem was quite different. I had accidentally removed some paths from my %PATH% variable. Simply restarting the command prompt solved it. It seems as though there was a JS runtime in one of those missing paths.

Answer 2

Ubuntu Users:

I had the same problem and I fixed it by installing nodejson my system independent of the gem.

on ubuntu its: sudo apt-get install nodejs

I'm using 64bit ubuntu 11.10

update: From @Galina 's answer below I'm guessing that the latest version of nodejs is required, so @steve98177 your best option on a redhat(or CentOS) box is to install from source code as @Galina did, but as you can't "make/install" on this box ?, I suggest you try to install a fedora rpm(long shot) https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager or find another RH/CentOs box(that you can 'make' on) and create your own rpm and install on original RH box(if old glibc on RH plays nice).

The real issue here(IMHO) is installing Gems that have dependencies on installed packages outside of the ruby environment, is there a way of knowing before installing ? an RFI for Gems or bundler ?

---

CentOS/RedHat Users:

sudo yum install nodejs

Answer 3

When you create an empty project, this line is commented in Gemfile. Just uncomment it and bundle!

gem 'therubyracer', :platforms => :ruby

Answer 4

add in your gemfile which is in the folder you have created: gem 'execjs' gem 'therubyracer'

Answer 5

In my case running the bundle command did the trick. I trust they find each other then.

Answer 6

I had this problem when using RubyMine (6.3.3). One day I tried to run my code, but it didn't work and complained about no JavaScript runtime found. I was able to run rails s though. The fix for me was creating a new Run configuration. Seems really bizarre that the Run configuration would become corrupt.