ExecJS and could not find a JavaScript runtime

ExecJS and could not find a JavaScript runtime

I’m trying to use the Mongoid / Devise Rails 3.1 template (Mongoid and Devise), and I keep getting an error stating ExecJS cannot find a JavaScript runtime. Fair enough when I didn’t have any installed, but I’ve tried installing Node.js, Mustang and the Ruby Racer, but nothing is working.
I could not find a JavaScript runtime. See sstephenson/ExecJS (GitHub) for a list of available runtimes (ExecJS::RuntimeUnavailable).
What do I need to do to get this working?

Solutions/Answers:

Solution 1:

Ubuntu Users

I’m on Ubuntu 11.04 and had similar issues. Installing Node.js fixed it.

As of Ubuntu 13.04 x64 you only need to run:

sudo apt-get install nodejs

This will solve the problem.


CentOS/RedHat Users

sudo yum install nodejs

Solution 2:

Just add ExecJS and the Ruby Racer in your gem file and run bundle install after.

gem 'execjs'

gem 'therubyracer'

Everything should be fine after.

Solution 3:

In your Gem file, write

gem 'execjs'
gem 'therubyracer'

and then run

bundle install

Everything works fine for me 🙂

Solution 4:

I had a similar problem: my Rails 3.1 app worked fine on Windows but got the same error as the OP when running on Linux. The fix that worked for me on both platforms was to add the following to my Gemfile:

gem 'therubyracer', :platforms => :ruby

The trick is knowing that :platforms => :ruby actually means only use this gem with “C Ruby (MRI) or Rubinius, but NOT Windows.”

Other possible values for :platforms are described in the bundler man page.

FYI: Windows has a builtin JavaScript engine which execjs can locate. On Linux there is not a builtin although there are several available that one can install. therubyracer is one of them. Others are listed in the execjs README.md.

Solution 5:

Adding the following gem to my Gemfile solved the issue:

gem 'therubyracer'

Then bundle your new dependencies:

$ bundle install

Solution 6:

An alternative way is to just bundle without the gem group that contains the things you don’t have.

So do:

bundle install --without assets

you don’t have to modify the Gemfile at all, providing of course you are not doing asset chain stuff – which usually applies in non-development environments. Bundle will remember your ‘–without’ setting in the .bundle/config file.