执行rails server
in `autodetect': Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes. (ExecJS::RuntimeUnavailable)
解决方案1：在GemFile（文件的位置在项目的首页中） 文件的末尾加上gem 'execjs'
gem 'therubyracer'
之后执行bundle install
解决方法2：
安装nodejs
lijg@lijg-desktop:~/workruby/helloapp$ sudo apt-cache search nodejs
[sudo] password for lijg:
coffeescript - interpreter and compiler for the CoffeeScript language
nodejs - Node.js event-based server-side javascript engine
nodejs-dbg - Node.js event-based server-side javascript engine (debug)
nodejs-dev - Development files for Node.js