ActionView::Template::Error (invalid regexp character): Error on newly created rails app on Windows

[KapilSachdev]

Hi @judofyr
The default JavaScript engine on Windows is now duktape.

The issue occurs when using the gem bootstrap-rubygem with duktape as JS runtime. Changing EXECJS_RUNTIME to any other resolves the issue.

# In `config/boot.rb`, changes the ExecJS runtime from Duktape to Node.
ENV['EXECJS_RUNTIME'] = 'Node

So looks like duktape has some compilation issues.

Steps to reproduce

• Use Windows-10
• Install RubyInstaller-2.5.1-1 (inkluding MSYS2 development tools)
• Then run:

gem install rails
rails new myapp
cd myapp

# Add the bootstrap gem to the Gemfile
gem 'bootstrap', '~> 4.1.1'

#  Import Bootstrap styles in app/assets/stylesheets/application.scss
@import "bootstrap";

# Create a controller and run server
rails g controller welcome index
rails s

Now Browse to http://localhost:3000/welcome/index

Expected behavior

It should show the index page with bootstrap css and js included.

Actual behavior

It raises the error

ActionView::Template::Error (invalid regexp character):
     5:     <%= csrf_meta_tags %>
     6:     <%= csp_meta_tag %>
     7:
     8:     <%= stylesheet_link_tag    'application', media: 'all', 'data-turbolinks-track': 'reload' %>
     9:     <%# <%= javascript_include_tag 'application', 'data-turbolinks-track': 'reload' %> %>
    10:   </head>
    11:

(execjs):24531
app/views/layouts/application.html.erb:8:in `_app_views_layouts_application_html_erb__393616251_122130440'

System configuration

Rails version: 5.2.0
Ruby version: ruby 2.5.1p57 (2018-03-29 revision 63029) [x64-mingw32]

Logging bootstrap-rubygem issue.

Including @larskanis due to PR

Thanks

[svaarala]

@KapilSachdev Could you provide the source line producing the error?

[KapilSachdev]

@svaarala , stylesheet_link_tag and javascript_include_tag both cause this issue. Hope this helps.

ActionView::Template::Error (invalid regexp character):
     5:     <%= csrf_meta_tags %>
     6:     <%= csp_meta_tag %>
     7:
     8:     <%= stylesheet_link_tag    'application', media: 'all', 'data-turbolinks-track': 'reload' %>
     9:     <% <%= javascript_include_tag 'application', 'data-turbolinks-track': 'reload' %> %>
    10:   </head>
    11:

(execjs):24531
app/views/layouts/application.html.erb:8:in `_app_views_layouts_application_html_erb__393616251_122130440'

(updated the above description too)

[svaarala]

But that's not javascript source line causing the issue ("invalid regexp character"). So I'm basically looking for the offending RegExp.

[KapilSachdev]

Well I haven't dig into that as I moved on to other stuff and that's why reported here.
I will look into it and inform.
Meanwhile, if you can have a look at the bootstrap gem would be great.

[KapilSachdev]

Hi @svaarala,

I think i found it.

function parseSourceMapInput(str) {
  return JSON.parse(str.replace(/^\)]}'[^\n]*\n/, ''));
}

When I execute this (using execjs with duktape), I could reproduce invalid regexp character error.

ExecJS.compile(source) # source being the JS

[judofyr]

Minimal test case:

Duktape::Context.new.eval_string('/]/.source')

The regexp /]/ seems to work nicely in Chrome.

[svaarala]

The technical background is that e.g. /]/ regexp syntax is only recommended for legacy environments, see https://www.ecma-international.org/ecma-262/6.0/#sec-additional-ecmascript-features-for-web-browsers. In practice much of the existing Javascript just assumes the browser-like legacy support.

Duktape supports parts of the legacy Annex B regexp syntax, but not all of it. However, /]/ should work at least in 2.0.0 and above:

((o) Duktape [linenoise] 2.0.0 (v2.0.0)
duk> r = /]/;
= {}
duk> r.exec(']')
= ["]"]

[judofyr]

I guess I should release Duktape 2.0 then

[judofyr]

Duktape.rb 2.0.1 is now released and things should work as expected.

[KapilSachdev]

@judofyr, Encountering new issue after the latest release.