set build as :
{ "scripts": { "build": "set NODE_ENV=production && webpack" } }
"build": "NODE_ENV='production' webpack",
.
|-- README.md
|-- app
| |-- README.md
| `-- index.js
|-- dist
| |-- README.md
| |-- bundle.js
| `-- index.html
|-- package-lock.json
|-- package.json
`-- webpack.config.js
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