bundle exec rake assets:precompile fails with `unexpected token`

Question

I'm ready to deploy my Rails 3.1 app into production, and since I'm using the asset pipeline, I need to precompile my assets. However, when I try this, I get an error apparently related to compiling jQuery:

$ bundle exec rake --trace assets:precompile
** Invoke assets:precompile (first_time)
** Execute assets:precompile
/home/adam/.rvm/rubies/ruby-1.9.3-p0/bin/ruby /home/adam/.rvm/gems/ruby-1.9.3-p0@rails-3.1/bin/rake assets:precompile:all RAILS_ENV=production RAILS_GROUPS=assets --trace
** Invoke assets:precompile:all (first_time)
** Execute assets:precompile:all
** Invoke assets:precompile:primary (first_time)
** Invoke assets:environment (first_time)
** Execute assets:environment
** Invoke environment (first_time)
** Execute environment
** Invoke tmp:cache:clear (first_time)
** Execute tmp:cache:clear
** Execute assets:precompile:primary
rake aborted!
399: unexpected token at '"/*!\u000a * jQuery JavaScript Library v1.7.1\u000a * http://jquery.com/\u000a *\u000a * Copyright 2011, John Resig\u000a * Dual licensed under the MIT or GPL Version 2 licenses.\u000a * http://jquery.org/license\u000a *\u000a * Includes Sizzle.js\u000a * http://sizzlejs.com/\u000a * Copyright 2011, The Dojo Foundation\u000a * Released under the MIT, BSD, and GPL Licenses.\u000a *\u000a * Date: Mon Nov 21 21:11:03 2011 -0500\u000a */\u000afunction addActiveScaffoldPageToHistory(a,b){if(typeof

[snip lots of stuff]

  (in /data/music/RotC/eventbook/app/assets/javascripts/application.js)
/home/adam/.rvm/gems/ruby-1.9.3-p0@rails-3.1/gems/json-1.6.4/lib/json/common.rb:148:in `parse'
/home/adam/.rvm/gems/ruby-1.9.3-p0@rails-3.1/gems/json-1.6.4/lib/json/common.rb:148:in `parse'
/home/adam/.rvm/gems/ruby-1.9.3-p0@rails-3.1/gems/multi_json-1.0.4/lib/multi_json/engines/json_common.rb:9:in `decode'
/home/adam/.rvm/gems/ruby-1.9.3-p0@rails-3.1/gems/multi_json-1.0.4/lib/multi_json.rb:76:in `decode'
/home/adam/.rvm/gems/ruby-1.9.3-p0@rails-3.1/gems/execjs-1.2.13/lib/execjs/external_runtime.rb:61:in `extract_result'
/home/adam/.rvm/gems/ruby-1.9.3-p0@rails-3.1/gems/execjs-1.2.13/lib/execjs/external_runtime.rb:27:in `block in exec'
/home/adam/.rvm/gems/ruby-1.9.3-p0@rails-3.1/gems/execjs-1.2.13/lib/execjs/external_runtime.rb:40:in `compile_to_tempfile'
/home/adam/.rvm/gems/ruby-1.9.3-p0@rails-3.1/gems/execjs-1.2.13/lib/execjs/external_runtime.rb:26:in `exec'

[snip lots more stuff]

Here's my application.js:

//= require jquery
//= require jquery_ujs
//= require jquery-ui
//
// N.B. jQuery requires have to come before this:
//= require active_scaffold

I'm using the default compressor, i.e. uglifier.

I've found that if I change config.assets.compress to false in config/environments/production.rb then it works fine, but of course my app would perform better if I could figure out a way to keep it as true.

I've looked at rake assets:precompile doesn't work (rails 3.1.1) and I don't think it's a duplicate because the error is undefined: Unexpected token: operator (<).

Any ideas? I'm vaguely suspicious of those unicode characters in the jQuery code, but I'm not sure how to prove or disprove that they are causing the problem.

Answer 1

I had this exact same problem and solved it, here are the details:

When you include one or more javascript files in your Rails 3.1 environment using application.js and //= require ..., Rails will wrap the contents of your file with a <script> ..filecontents.. </script>. You can verify this by running your site in development mode and doing a View | Source.

The problem is, in development mode, if you are not actually using that script, it may appear to work fine. But, Essentially, what you have is <script><script> ..filecontents.. </script></script>.

However, when you attempt to PRECOMPILE the assets, something in that compiling process (sorry - I do not know what exactly) gags on the "<" in the inner script token.

Double-check your included .js files and, if any of them are wrapped by <script> ... </script> remove those surrounding tags.

You should see that, in Development, everything still looks fine if you View Page Source. And, when you precompile your assets, the error should go away.

I ran into this problem with Google's recommended google-analytics javascript snippet and removing the script wrapper from the included file solved the problem.

Answer 2

Here's how I debugged this.

Locally, run this

RAILS_ENV=production bundle exec rake assets:precompile

Try to find out where it chokes (the script right before the choking is the file you'll want to look at). Look at all the requires.

In my case, I had a file that ended in .js when it should've been .jsx and that's what fixed it.

Answer 3

I had the very same problem.

Even though I did not have a <script> tag in my javascript files, Dave's suggestion helped me a lot!

I was able to spot a comment on a external lib I was loading in my application.js:

<!-- Hotjar Tracking Code for (...) ->

That single comment was breaking my uglifier compression and it took me a long time to find it and even possibly think it was the culprit.

So, also watch out for comments in the begining of JS files, as the might break your compression.