Webpack 4 config starter

package.json

{
  "name": "knitcodemonkey_starter",
  "version": "1.0.0",
  "description": "KnitCodeMonkey's Starter",
  "repository": {},
  "scripts": {
    "init": "rm -rf node_modules; npm install; npm run build; npm run docs;",
    "dev": "webpack --env.NODE_ENV=dev --mode=development --profile --colors",
    "prod": "webpack --env.NODE_ENV=production --env.production --mode=production --optimize-minimize --progress --profile --colors",
    "watch": "webpack -d --env.NODE_ENV=dev --mode=development -w --colors &",
    "analyze": "rm ./stats.json; webpack --json > stats.json --env.NODE_ENV=production --env.production --mode=production --optimize-minimize --progress --profile --colors; ./node_modules/.bin/webpack-bundle-analyzer stats.json",
    "docs": "./docs"
  },
  "devDependencies": {
    "babel-cli": "^6.26.0",
    "babel-core": "^6.26.0",
    "babel-loader": "^7.1.4",
    "babel-preset-env": "^1.6.1",
    "babel-preset-react": "^6.3.13",
    "babel-preset-stage-2": "^6.3.13",
    "css-loader": "^0.28.11",
    "es-module-loader": "^2.2.8",
    "esdoc": "^1.0.4",
    "esdoc-jsx-plugin": "^1.0.0",
    "esdoc-standard-plugin": "^1.0.0",
    "eslint": "^4.18.1",
    "eslint-plugin-jsx-a11y": "^6.0.3",
    "expose-loader": "^0.7.5",
    "extract-text-webpack-plugin": "^4.0.0-beta.0",
    "file-loader": "^1.1.11",
    "jsx-loader": "^0.13.2",
    "node-sass": "^4.8.3",
    "optimize-css-assets-webpack-plugin": "^4.0.0",
    "promise": "^8.0.1",
    "react-dropzone": "^4.2.9",
    "react-redux": "^5.0.7",
    "redux": "^3.7.2",
    "redux-devtools": "^3.4.1",
    "require-dir": "^1.0.0",
    "sass-loader": "^6.0.7",
    "script-loader": "^0.7.2",
    "sinon": "^4.4.6",
    "style-loader": "^0.20.3",
    "uglify-js": "^3.3.16",
    "uglifyjs-webpack-plugin": "^1.2.4",
    "url-loader": "^1.0.1",
    "webpack": "^4.1.1",
    "webpack-bundle-analyzer": "^2.11.1",
    "webpack-cli": "^2.0.12",
    "webpack-stream": "^4.0.2"
  },
  "dependencies": {
    "classnames": "^2.2.5",
    "react": "^15.6.2",
    "react-dom": "^15.6.2",
  }
}

webpack.config.js

const webpack = require("webpack");
const path = require("path");
const ExtractTextPlugin = require("extract-text-webpack-plugin");
const UglifyJsPlugin = require("uglifyjs-webpack-plugin");

module.exports = env => {
  const isProd = env.NODE_ENV === "production";
  const plugins = [
    new ExtractTextPlugin({
      filename: getPath => getPath("[name].css").replace("css/js", "css"),
      allChunks: true
    })
  ];
  if (isProd === "production") {
    plugins.push(
      new UglifyJsPlugin({
        parallel: 8,
        cache: true
      })
    );
  }

  return {
    devtool: isProd ? false : "source-map",
    entry: {
      file1: "./src/file1.js",
      file2: "./src/file2.js"
    },
    output: {
      path: path.resolve(__dirname, "dist/"),
      filename: "[name].js"
    },
    module: {
      rules: [
        {
          test: require.resolve("react"),
          use: [
            {
              loader: "expose-loader",
              options: "React"
            }
          ]
        },
        {
          test: /\.(js|jsx)?$/,
          loader: "babel-loader",
          exclude: /node_modules/,
          query: {
            presets: ["react", "stage-2", "env"]
          }
        },
        {
          // inline base64 URLs for <=8k images, direct URLs for the rest
          test: /\.(png|jpg|gif)$/,
          use: [
            {
              loader: "url-loader",
              options: {
                limit: 8192,
                name: "./images/[name]-[hash:6].[ext]?[hash]"
              }
            }
          ]
        },
        {
          test: /\.scss$/,
          use: ExtractTextPlugin.extract({
            use: ["style-loader", "css-loader", "sass-loader"]
          })
        },
        {
          // For fonts files
          test: /\.(ttf|eot|svg|woff(2)?)(\?[a-z0-9]+)?$/,
          use: [
            {
              // url-loader will fallback to file-loader if limit is exceeded. It will pass all of the query args along.
              loader: "url-loader",
              options: {
                limit: 1,
                name: "./fonts/[name]-[hash:6].[ext]?[hash]"
              }
            }
          ]
        },

        {
          test: /\.css$/,
          use: ExtractTextPlugin.extract({
            fallback: "style-loader",
            use: "css-loader"
          })
        }
      ]
    },
    externals: {
      jquery: "$",
    },
    plugins,
    optimization: {
      splitChunks: {
        cacheGroups: {
          commons: {
            name: "commons",
            chunks: "initial",
            minChunks: 2
          }
        }
      }
    }
  };
};