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

On Ubuntu, I had to sudo apt-get update and then the nodejs install worked.

Answer 2

I had similar issues on ubuntu 12.04. Installing Node.js fixed it.

Answer 3

when i generate rails g controller i got the same error. After that when do the following changes on Gemfile(in rails 4) everything went smooth.The changes i made was

gem 'execjs'
gem 'therubyracer', "0.11.4"
After that i can able to run the server and able to do all basic operations on the application.

Answer 4

In your gemfile add:

gem 'execjs'
gem 'therubyracer', :platforms => :ruby

For more details: ExecJS and could not find a JavaScript runtime

Answer 5

I have pulled my hair out with this error a few time. I have managed to make it sometime disappear by restarting Apache/Nginx.

So I fixed it the same way as above, by adding the following to the GEM file:

gem 'execjs'
gem 'therubyracer', :platforms => :ruby

and then I DELETED my gemfile.lock file and then reran "bundle install". I found only then did "bundle install" actually install the correct libraries etc.

Answer 6

I am using Ubuntu 11.10- 32 bit with ruby 1.9.3p194, rails 3.2.3, gem 1.8.24. Was receiving the same Javascript error while running "script/rails console".

However doing a "sudo apt-get install nodejs" solved my issue.