在heroku上部署Rails应用程序时，出现以下错误，
remote: Bundle completed (163.81s)
remote: Cleaning up the bundler cache.
remote: -----> Installing node-v8.10.0-linux-x64
remote: -----> Detecting rake tasks
remote: -----> Preparing app for Rails asset pipeline
remote: Running: rake assets:precompile
remote: Yarn executable was not detected in the system.
remote: Download Yarn at https://yarnpkg.com/en/docs/install
remote: rake aborted!
remote: Uglifier::Error: Unexpected token punc «;», expected punc «,»
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/uglifier-4.1.20/lib/uglifier.rb:234:in `parse_result'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/uglifier-4.1.20/lib/uglifier.rb:216:in `run_uglifyjs'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/uglifier-4.1.20/lib/uglifier.rb:168:in `compile'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/compressing.rb:65:in `block in js_compressor='
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/legacy_proc_processor.rb:31:in `call'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/processor_utils.rb:75:in `call_processor'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/processor_utils.rb:57:in `block in call_processors'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/processor_utils.rb:56:in `reverse_each'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/processor_utils.rb:56:in `call_processors'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/loader.rb:134:in `load_from_unloaded'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/loader.rb:60:in `blockin load'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/loader.rb:317:in `fetch_asset_from_dependency_cache'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/loader.rb:44:in `load'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/cached_environment.rb:20:in `block in initialize'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/cached_environment.rb:47:in `load'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/base.rb:66:in `find_asset'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/base.rb:73:in `find_all_linked_assets'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/manifest.rb:142:in `block in find'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/legacy.rb:114:in `block (2 levels) in logical_paths'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/path_utils.rb:228:in `block in stat_tree'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/path_utils.rb:212:in `block in stat_directory'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/path_utils.rb:209:in `each'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/path_utils.rb:209:in `stat_directory'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/path_utils.rb:227:in `stat_tree'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/legacy.rb:105:in `each'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/legacy.rb:105:in `block in logical_paths'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/legacy.rb:104:in `each'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/legacy.rb:104:in `logical_paths'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/manifest.rb:140:in `find'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/sprockets/manifest.rb:186:in `compile'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-rails-3.2.1/lib/sprockets/rails/task.rb:68:in `block (3 levels) in define'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-3.7.2/lib/rake/sprocketstask.rb:147:in `with_logger'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/sprockets-rails-3.2.1/lib/sprockets/rails/task.rb:67:in `block (2 levels) in define'
remote: /tmp/build_eb48b48285b82dae89f9dfd764c51c22/vendor/bundle/ruby/2.4.0/gems/rake-12.3.2/exe/rake:27:in `'
remote: Tasks: TOP => assets:precompile
remote: (See full trace by running task with --trace)
remote:
remote: !
remote: ! Precompiling assets failed.
remote: !
remote: ! Push rejected, failed to compile Ruby app.
remote:
remote: ! Push failed
remote: Verifying deploy...
我已经将production.rb中的行修改为
config.assets.js_compressor = Uglifier.new(harmony: true)
但错误仍然存在。
答案 0 :(得分：0)
似乎出现了问题，因为您的Sprockets或Rails版本无法与较新的Uglifier很好地配合使用。至少在Rails 3.2.22中，会生成.map文件，然后将其视为下一个后缀。例如。链轮试图将application.js.map压缩为js文件。
一种解决方案是通过在您的config/environments/production.rb文件（或您喜欢的任何配置文件）中添加一行来告诉Sprockets忽略地图文件：
config.assets.precompile[0] = Proc.new { |path| !File.extname(path).in?(['.js', '.css', '.map']) }
在复制粘贴上面的代码之前，您应验证要替换先前存在的config.assets.precompile数组中的正确项目。该数组包含确定哪些文件被处理的过程。对我来说，数组中有两个项目，第一个如下：
#<Proc:0x0055819620f6f8@/home/me/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/railties-3.2.22/lib/rails/application/configuration.rb:48>
查看上述proc的定义的指示位置（gems/railties-3.2.22/lib/rails/application/configuration.rb:48）会显示：
Proc.new{ |path| !File.extname(path).in?(['.js', '.css']) }
...选择每个非js，非css文件。将'.map'添加到该排除列表中将防止.map文件通过压缩器被馈入。