example.js

console.log(process.env.NODE_ENV);

import "./example.css";
import "react";
import "react-dom";
import "acorn";
import "core-js";
import "date-fns";
import "lodash";
import * as _ from "lodash-es";
console.log(_);

webpack.config.js

const path = require("path");
module.exports = (env = "development") => ({
	mode: env,
	infrastructureLogging: {
		// Optional: print more verbose logging about caching
		level: "verbose"
	},
	cache: {
		type: "filesystem",

		// changing the cacheDirectory is optional,
		// by default it will be in `node_modules/.cache`
		cacheDirectory: path.resolve(__dirname, ".cache"),

		// Add additional dependencies to the build
		buildDependencies: {
			// recommended to invalidate cache on config changes
			// This also makes all dependencies of this file build dependencies
			config: [__filename]
			// By default webpack and loaders are build dependencies
		}
	},
	module: {
		rules: [
			{
				test: /\.css$/,
				use: ["style-loader", "css-loader"]
			}
		]
	}
});

Info

Unoptimized

asset output.js 3.92 MiB [emitted] (name: main)
chunk output.js (main) 2.8 MiB (javascript) 1.58 KiB (runtime) [entry]
  > ./example.js main
  cached modules 2.8 MiB (javascript) 1.58 KiB (runtime) [cached] 1191 modules
webpack 5.0.0 compiled successfully

Production mode

asset output.js 544 KiB [emitted] [minimized] [big] (name: main) 1 related asset
chunk (runtime: main) output.js (main) 1.89 MiB (javascript) 1.33 KiB (runtime) [entry]
  > ./example.js main
  cached modules 1.89 MiB (javascript) 1.33 KiB (runtime) [cached] 570 modules

WARNING in asset size limit: The following asset(s) exceed the recommended size limit (244 KiB).
This can impact web performance.
Assets: 
  output.js (544 KiB)

WARNING in entrypoint size limit: The following entrypoint(s) combined asset size exceeds the recommended limit (244 KiB). This can impact web performance.
Entrypoints:
  main (544 KiB)
      output.js

WARNING in webpack performance recommendations: 
You can limit the size of your bundles by using import() or require.ensure to lazy load some parts of your application.
For more info visit https://webpack.js.org/guides/code-splitting/

webpack 5.0.0 compiled with 3 warnings