Cannot turn off es5 compile

[disrael]

In package.json

"browserslist": {
"development": [
"last 1 chrome versions"
],
"production": [
"last 1 chrome versions"
]
},
"devDependencies": {
"enzyme": "^3.5.0",
"react-scripts": "2.0.0-next.a671462c",
"redux-logger": "^3.0.6",
"redux-testkit": "^1.0.6",
"selenium-webdriver": "^4.0.0-alpha.1",
"source-map-explorer": "^1.6.0",
"standard": "^11.0.1"
}

but

(main) disrael@disrael-Lemur:~/dev/uclusion_web_ui$ npm run-script build

test-app@0.1.0 build /home/disrael/dev/uclusion_web_ui
react-scripts build

Creating an optimized production build...
Failed to compile.

Failed to minify the code from this file:

../javascript_sdk/src/uclusion.js:14 

Read more here: http://bit.ly/2tRViJ9

npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! test-app@0.1.0 build: react-scripts build
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the test-app@0.1.0 build script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

Where the error message is pointing to issues compiling to es5.

#4421 was closed but without sufficient documentation to achieve an es6 only compile.

[disrael]

Looking at https://github.com/facebook/create-react-app/blob/next/packages/react-scripts/config/webpack.config.prod.js isn't the minimizer just hard coded to 5?

optimization: {
minimizer: [
new UglifyJsPlugin({
uglifyOptions: {
parse: {
// we want uglify-js to parse ecma 8 code. However, we don't want it
// to apply any minfication steps that turns valid ecma 5 code
// into invalid ecma 5 code. This is why the 'compress' and 'output'
// sections only apply transformations that are ecma 5 safe
// https://github.com//pull/4234
ecma: 8,
},
compress: {
ecma: 5,
warnings: false,
// Disabled because of an issue with Uglify breaking seemingly valid code:
// https://github.com//issues/2376
// Pending further investigation:
// https://github.com/mishoo/UglifyJS/issues/2011
comparisons: false,
},
mangle: {
safari10: true,
},
output: {
ecma: 5,
comments: false,
// Turned on because emoji and regex is not minified properly using default
// https://github.com//issues/2488
ascii_only: true,
},
},
// Use multi-process parallel running to improve the build speed
// Default number of concurrent runs: os.cpus().length - 1
parallel: true,
// Enable file caching
cache: true,
sourceMap: shouldUseSourceMap,
}),
new OptimizeCSSAssetsPlugin({ cssProcessorOptions: { safe: true } }),
],

[disrael]

Oh never mind the ecma: 5 hard code because changing it to 6 wouldn't help. I think you have to use https://www.npmjs.com/package/uglify-es instead of UglifyJS.

[Timer]

Hi! Dependencies will be compiled in v2 so this won't be an issue anymore. See #5024, thanks!