Removing development files from bundle (using NormalModuleReplacementPlugin)

test.js

// This import should be dropped in production,
// because it's very large and contains development data 
// (like locales for all languages).
import load from './very.large'

export const main = () => {
  let data = {}
  
  if (process.env.NODE_ENV !== 'development') {
    data = load()
  }
}

very.large.js

export default () => 'VERY LARGE VERY LARGE VERY LARGE VERY LARGE VERY LARGE VERY LARGE VERY LARGE VERY LARGE VERY LARGE VERY LARGE'

very.large.replacement.js

// Empty file

webpack.config.js

const webpack = require('webpack');

module.exports = {
  entry: '...',
  output: { /* ... */ },
  
  plugins: process.env.NODE_ENV === 'development' ?
    [] : [
      // This will replace every import matching /very\.large\.js$/ with ./very.large.replacement.js
      // See https://webpack.js.org/plugins/normal-module-replacement-plugin/
      new webpack.NormalModuleReplacementPlugin(/very\.large\.js$/, './very.large.replacement.js')
    ]
};