Unicorn Error Occuerd

/home/deploy/.bundler/sampleapplication/ruby/2.1.0/gems/execjs-2.2.2/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)