为什么gem`therubyracer`默认在Gemfile中注释掉了?

时间:2013-09-08 19:11:20

标签: ruby-on-rails ruby-on-rails-4 rubygems

我创建了一个rails应用程序,并尝试启动rails服务器。我收到了以下错误:

/home/ritesh/.rvm/gems/ruby-1.9.3-p429/gems/execjs-2.0.1/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)
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429/gems/execjs-2.0.1/lib/execjs.rb:5:in `<module:ExecJS>'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429/gems/execjs-2.0.1/lib/execjs.rb:4:in `<top (required)>'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429/gems/uglifier-2.2.1/lib/uglifier.rb:3:in `require'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429/gems/uglifier-2.2.1/lib/uglifier.rb:3:in `<top (required)>'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:72:in `require'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:72:in `block (2 levels) in require'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:70:in `each'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:70:in `block in require'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:59:in `each'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429@global/gems/bundler-1.3.5/lib/bundler/runtime.rb:59:in `require'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429@global/gems/bundler-1.3.5/lib/bundler.rb:132:in `require'
from /home/ritesh/projects/interview/config/application.rb:7:in `<top (required)>'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429/gems/railties-4.0.0/lib/rails/commands.rb:76:in `require'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429/gems/railties-4.0.0/lib/rails/commands.rb:76:in `block in <top (required)>'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429/gems/railties-4.0.0/lib/rails/commands.rb:73:in `tap'
from /home/ritesh/.rvm/gems/ruby-1.9.3-p429/gems/railties-4.0.0/lib/rails/commands.rb:73:in `<top (required)>'
from bin/rails:4:in `require'
from bin/rails:4:in `<main>'

虽然我可以通过从gem 'therubyracer', platforms: :ruby删除Gemfile行之前的评论来解决此问题。

为什么当我们在启动rails应用程序时首先需要它时,这个gem被注释掉了?

1 个答案:

答案 0 :(得分:21)

因为如果在机器上安装了另一个JavaScript运行时(如Node.js),Rails可以使用它,并且不需要therubyracer。

Rails使用ExecJS加载JavaScript运行时。有关ExecJS的更多信息,请参阅其Github页面:https://github.com/sstephenson/execjs。自述文件提供了可用运行时列表(作为错误日志说明)。

根据您的部署过程和生产环境,您使用哪个JavaScript运行时可能并不重要。有些人对therubyracer库的大小有疑问(参见Rails - Could not find a JavaScript runtime?),在生产服务器上安装它可能并不聪明。