ExecJS::ProgramError: Unexpected token punc «(», expected punc «:» when running rake assets:precompile on production

Question

When deploying my Rails app I get the following error:

rake aborted!
   ExecJS::ProgramError: Unexpected token punc «(», expected punc «:» (line: 15, col: 14         


        

Answer 1

December/2019 answer: starting on version 4.2.0 (released in Sept/2019), Uglifier now shows a beautiful (colored!) debug output showing you the offending line of code.

I was having a Uglifier::Error: Unexpected character ''` error and I couldn't find it even following all the other solutions in this page.

So go to your Gemfile, and set your Uglifier to be at least 4.2:

# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 4.2'

Run bundle update uglifier to update it.

And then just look at the output, it will show you something like this: