Building exception (uglify) when using --prod

[ghost]

Short description of the problem:

I'm getting an exception when creating Ionic builds with --prod flag, caused by uglifyjs.

What behavior are you expecting?

I expect that uglifyjs properly uglifies all my code and the build can be run successfully.

Steps to reproduce:

1. ionic cordova build ios --prod

[INFO] Running app-scripts build: --prod --platform ios --target cordova
       
[08:29:47]  build prod started ... 
[08:29:48]  clean started ... 
[08:29:48]  clean finished in less than 1 ms 
[08:29:48]  copy started ... 
[08:29:48]  ngc started ... 
[08:30:01]  ngc finished in 13.09 s 
[08:30:01]  preprocess started ... 
[08:30:01]  deeplinks started ... 
[08:30:02]  deeplinks finished in 1.13 s 
[08:30:02]  optimization started ... 
[08:30:06]  copy finished in 18.64 s 
[08:30:19]  optimization finished in 16.99 s 
[08:30:19]  preprocess finished in 18.12 s 
[08:30:19]  webpack started ... 
[08:31:30]  webpack finished in 71.62 s 
[08:31:30]  sass started ... 
[08:31:30]  uglifyjs started ... 
[08:31:32]  sass finished in 1.46 s 
[08:31:32]  cleancss started ... 
[08:31:33]  cleancss finished in 1.14 s 
Error: Uglify failed: Unexpected token operator «=», expected punc «,» in undefined at line undefined, col undefined, pos undefined
    at new BuildError (/Users/user/Development/app/sources/node_modules/@ionic/app-scripts/dist/util/errors.js:16:28)
    at taskReject (/Users/user/Development/app/sources/node_modules/@ionic/app-scripts/dist/worker-process.js:36:22)
    at /Users/user/Development/app/sources/node_modules/@ionic/app-scripts/dist/worker-process.js:14:13

Which @ionic/app-scripts version are you using?
2.1.4

Other information: (e.g. stacktraces, related issues, suggestions how to fix, stackoverflow links, forum links, etc)
I know that this has been an issue with older Ionic version already, where one could install "uglifyjs#harmony" to fix the issue within the app-scripts dependency. But this doesn't seem to work anymore. I've seen this issue in many places and quite often, hence that's something you should really have a look at.

[stevengunneweg]

I posted a temporary workaround for a failing --prod build in #1243

EDIT: I don't see the error myself, my build just gets stuck but maybe the workaround will work for you as well

[danbucholtz]

@dani-inside,

Is your project available online for me to take a look?

Thanks,
Dan

[ghost]

Thanks guys. @danbucholtz : Unfortunately not. Meanwhile (yesterday) I managed to fix the issue by updating the app-scripts to latest release 3.0.0. After updating the custom configs (webpack.config.js / copy.config.js) I could build the project without any issues, with and without the --prod flag.

As the issue is fixed for me, you may close the issue.