uglifyjs-webpack-plugin@^0.4.6 and uglifyjs-webpack-plugin@^1.1.0 both in use

[thijsfranck]

• I have checked the superset logs for python stacktraces and included it here as text if any
• I have reproduced the issue with at least the latest released version of superset
• I have checked the issue tracker for the same issue and I haven't found one similar

Superset version

commit 84a7730 - master branch

Expected results

Compile javascript containing ES6 constructs successfully using uglifyjs-webpack-plugin^1.1.2

Actual results

UglifyJs produces the following errors:

`ERROR in dashboard.ec6c8da707d118e14e39.entry.js from UglifyJs Unexpected token: punc (.) [dashboard.ec6c8da707d118e14e39.entry.js:266806,11]

ERROR in explore.4ffc79b5c4308af98750.entry.js from UglifyJs Unexpected token: punc (.) explore.4ffc79b5c4308af98750.entry.js:266286,11]`

Steps to reproduce

The first error is being caused by this line of code:

if (new.target == ConceptRegistry) {

The second error is being caused by this line of code (it's actually the same):

if (new.target == ConceptRegistry) {

This code runs just fine, but the uglification script is having some trouble with it. I expect this is because this syntax was only introduced recently (ES6). The uglification plugin version 1.0.0 and up should support this. The latest version of superset has version 1.1.0 configured. In my problem solving process, I have upgraded this to version 1.1.2 to see if this changes things (it does not). Thus, the package.json is set up as follows:

devdependencies{ "uglifyjs-webpack-plugin": "^1.1.2" }

However, in the yarn.lock file I am finding this:

uglifyjs-webpack-plugin@^0.4.6:
version "0.4.6"
resolved "https://registry.yarnpkg.com/uglifyjs-webpack-plugin/-/uglifyjs-webpack-plugin-0.4.6.tgz#b951f4abb6bd617e66f63eb891498e391763e309"
dependencies:
source-map "^0.5.6"
uglify-js "^2.8.29"
webpack-sources "^1.0.1"

uglifyjs-webpack-plugin@^1.1.2:
version "1.1.2"
resolved "https://registry.yarnpkg.com/uglifyjs-webpack-plugin/-/uglifyjs-webpack-plugin-1.1.2.tgz#8a9abc238d01a33daaf86fa9a84c7ebc1e67b0f9"
dependencies:
cacache "^10.0.0"
find-cache-dir "^1.0.0"
schema-utils "^0.3.0"
source-map "^0.6.1"
uglify-es "^3.2.0"
webpack-sources "^1.0.1"
worker-farm "^1.4.1"

So, there is a dependency to the new version of the uglification plugin, which supports my syntax, and an older version which does not. Since I am seeing errors, I am guessing the latter one is used at the moment. I have not yet found the configuration setting that is managing this. Is this behaviour intentional, or is this a bug? Where can I find the additional configuration that I am currently still missing?

[rhunwicks]

Our attempt to build the JavaScript assets is failing with:

ERROR in dashboard.e12007b38f5d226a9398.entry.js from UglifyJs
Unexpected token: keyword (const) [dashboard.e12007b38f5d226a9398.entry.js:250449,7]

ERROR in explore.b068173a7061b4b69f89.entry.js from UglifyJs
Unexpected token: keyword (const) [explore.b068173a7061b4b69f89.entry.js:250450,7]

https://stackoverflow.com/questions/42375468/uglify-syntaxerror-unexpected-token-punc/46294198#46294198 explains that the installed "uglifyjs-webpack-plugin": "^1.1.0", from package.json won't get used.

We solved the problem by removing the embedded Webpack version prior to running the build:

rm -rf ./node_modules/webpack/node_modules/uglifyjs-webpack-plugin
npm run prod

Once the desired "uglifyjs-webpack-plugin": "^1.1.0", was being used we had to update the webpack.config.js to match the config requirements for the later package:

const UglifyJsPlugin = require('uglifyjs-webpack-plugin')

if (process.env.NODE_ENV === 'production') {
  // Using settings suggested in https://github.com/webpack/webpack/issues/537
  const UJSplugin = new UglifyJsPlugin({
    uglifyOptions: {
      ecma: 8,
      compress:  {
        warnings: false
      },
    },
    sourceMap: true,
    parallel: 4
  });
  config.plugins.push(UJSplugin);
}

[kristw]

Fixed by #5983