【转】rails 遇到 Could not find a JavaScript runtime execjs错误（ubuntu）

当我运行

$rails s

遇到下面错误

/var/lib/gems/2.0.0/gems/execjs-2.2.1/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)

在ubuntu环境下解决方法如下 

sudo apt-get install python-software-properties  
sudo add-apt-repository ppa:chris-lea/node.js  
sudo apt-get update  
sudo apt-get install nodejs