getting start with rubyOnRails

照着rubyOnRails的guide编写自己的第一个blog，在 rake db:create数据库时碰到错误：

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

解决方法：

In your Gemfile

write this

gem 'execjs'

gem 'therubyracer'


and then run

bundle install