ExecJS::ProgramError: Unexpected token: name (option)

问题

My app runs fine on local environment. I was trying to git push a build to heroku. My commands are:

bundle install
git add .
git commit -am "abcdef"
git push heroku master

I then encountered an issue with assets:precompile

remote: -----> Preparing app for Rails asset pipeline
remote:        Running: rake assets:precompile
remote:        I, [2016-01-04T08:32:35.471098 #1018]  INFO -- : Writing /tmp/build_5d68c6d2f7845ca719a5f77705a12798/public/assets/recruiters-e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855.js
remote:        I, [2016-01-04T08:32:35.471825 #1018]  INFO -- : Writing /tmp/build_5d68c6d2f7845ca719a5f77705a12798/public/assets/recruiters-e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855.js.gz
remote:        I, [2016-01-04T08:32:35.477826 #1018]  INFO -- : Writing /tmp/build_5d68c6d2f7845ca719a5f77705a12798/public/assets/recruiters-e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855.css
remote:        I, [2016-01-04T08:32:35.477974 #1018]  INFO -- : Writing /tmp/build_5d68c6d2f7845ca719a5f77705a12798/public/assets/recruiters-e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855.css.gz
remote:        I, [2016-01-04T08:32:35.575303 #1018]  INFO -- : Writing /tmp/build_5d68c6d2f7845ca719a5f77705a12798/public/assets/events-e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855.js
remote:        I, [2016-01-04T08:32:35.575465 #1018]  INFO -- : Writing /tmp/build_5d68c6d2f7845ca719a5f77705a12798/public/assets/events-e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855.js.gz
remote:        I, [2016-01-04T08:32:35.623887 #1018]  INFO -- : Writing /tmp/build_5d68c6d2f7845ca719a5f77705a12798/public/assets/events-31e95c603f03e300e73e01cd6ee747799da57b4d12924aa979e0fa0749681cca.css
remote:        I, [2016-01-04T08:32:35.624406 #1018]  INFO -- : Writing /tmp/build_5d68c6d2f7845ca719a5f77705a12798/public/assets/events-31e95c603f03e300e73e01cd6ee747799da57b4d12924aa979e0fa0749681cca.css.gz
remote:        rake aborted!
remote:        ExecJS::ProgramError: Unexpected token: name (option) (line: 242, col: 14, pos: 7159)
remote:        Error
remote:        at new JS_Parse_Error (/tmp/execjs20160104-1018-1ens1gjjs:2659:11936)
remote:        at js_error (/tmp/execjs20160104-1018-1ens1gjjs:2659:12155)
remote:        at croak (/tmp/execjs20160104-1018-1ens1gjjs:2659:20622)
remote:        at token_error (/tmp/execjs20160104-1018-1ens1gjjs:2659:20759)
remote:        at unexpected (/tmp/execjs20160104-1018-1ens1gjjs:2659:20847)
remote:        at semicolon (/tmp/execjs20160104-1018-1ens1gjjs:2659:21320)
remote:        at simple_statement (/tmp/execjs20160104-1018-1ens1gjjs:2659:24179)
remote:        at /tmp/execjs20160104-1018-1ens1gjjs:2659:22152
remote:        at /tmp/execjs20160104-1018-1ens1gjjs:2659:21493
remote:        at block_ (/tmp/execjs20160104-1018-1ens1gjjs:2659:26198)new JS_Parse_Error ((execjs):2659:11936)
remote:        js_error ((execjs):2659:12155)
remote:        croak ((execjs):2659:20622)
remote:        token_error ((execjs):2659:20759)
remote:        unexpected ((execjs):2659:20847)
remote:        semicolon ((execjs):2659:21320)
remote:        simple_statement ((execjs):2659:24179)
remote:        (execjs):2659:22152
remote:        (execjs):2659:21493
remote:        block_ ((execjs):2659:26198)

Note that I have controller-specific assets compile (see below). I wonder if that would cause the issue.

views/layout/application.html.erb

<%= stylesheet_link_tag "application", params[:controller], :media => "all", 'data-turbolinks-track' => true %>
<%= javascript_include_tag 'application', params[:controller], 'data-turbolinks-track' => true %>

initializers/assets.rb

# Compile controller assets
%w( recruiters events forms candidates ).each do |controller|
  Rails.application.config.assets.precompile += ["#{controller}.js", "#{controller}.css"]
end

Any thoughts or suggestions?

Update I was able to locate where the issue is from. Though I'm not sure what is wrong and why it works fine locally.

 238        if (fieldClass.match(/(select|checkbox-group|radio-group)/)) {
 239          previewData.values = [];
 240  
 241          $('.sortable-options li', field).each(function() {
 242            let option = {};
      ==============^
      SyntaxError: missing ; before statement
 243            option.selected = $('.select-option', $(this)).is(':checked');
 244            option.value = $('.option-value', $(this)).val();
 245            option.label = $('.option-label', $(this)).val();
 246  
 247            previewData.values.push(option);
 248          });
 249        }

Syntax Error