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

$ rails server

/home/user/.rvm/gems/ruby-1.9.3-p194/gems/execjs-1.4.0/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/user/.rvm/gems/ruby-1.9.3-p194/gems/execjs-1.4.0/lib/execjs.rb:5:in `<module:ExecJS>'

 

The reason for this issue is missing Node JS Package Manager. Check this link for how to install package manger based on your operating system.

https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager

I hope it may help you to solve the problem.