rake assets:precompile doesn't work (rails 3.1.1)

Question

I am deploying to heroku yet I saw that the css files aren't being served (they also cannot be found on heroku).

I read that I need to do rake assets:precompile locally at first yet when I do it I get:

C:\project>bundle exec rake assets:precompile --trace

** Invoke assets:precompile (first_time)
** Execute assets:precompile
rake aborted!
undefined: Unexpected token: operator (<)
  (in C:/project/app/assets/javascripts/application.js)

Tasks: TOP => assets:precompile
(See full trace by running task with --trace)

I have nothing in application.js so I don't understand where the error is..

application.js is

// This is a manifest file that'll be compiled into including all the files listed below.
// Add new JavaScript/Coffee code in separate files in this directory and they'll automatically
// be included in the compiled file accessible from http://example.com/assets/application.js
// It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
// the compiled file.
//
//= require jquery
//= require jquery_ujs
//= require_tree .

Thank you

Update

If removing a .js.erb file I get the following error

C:\project>bundle exec rake assets:precompile RAILS_ENV=production --trace
** Invoke assets:precompile (first_time)
** Execute assets:precompile
rake aborted!
706: unexpected token at 'C:\Users\me\AppData\Local\Temp\execjs20111021-6448-ei2nm3.js(2, 3) Microsoft JScript runtime error: Out of memory

'
  (in C:/project/app/assets/javascripts/application.js)

Tasks: TOP => assets:precompile
(See full trace by running task with --trace)

Still have problems with erb css and js files not compiling...

This doesn't seem to end.. Thanks

Answer 1

I've been struggling with this trying to deploy to a staging server. The solution that works for me is to make sure you have the following in your config/environments/[your_environment].rb file:

config.assets.compress = false

By default, the compressors aren't available in environment other than production, which is why the precompile was failing.

Answer 2

I have the same issue here! In my case, what causes this issue is that, I add a new JS file to javascript folder, and I got an undefined: Unexpected token: operator (<) error while I tried to run precompile command. So I look into the new js file and found there is a HTML style comment <!-- --> in that file. I remove it and life is good now!

So try to find out is there any HTML style comment <!-- --> in your js file and just remove those comments. This is especially true when some JS code is copied from html file!