Example webpack config that uses one entry per file (see `clientEntry` function).

webpack.config.js

/**
 * Copyright 2020 Robert M. Vunabandi. All Rights Reserved.
 */

const fs = require("fs")
const path = require("path")

const nodeExternals = require("webpack-node-externals");
const webpack = require("webpack")

const POLYFILL = "@babel/polyfill"
const CLIENT_DIR_PATH = "./src/client/pages/"

// Common configurations between client and server
const alias = {}
alias["@client"] = path.resolve(__dirname, "src/client")
alias["@components"] = path.resolve(__dirname, "src/client/components")
alias["@enums"] = path.resolve(__dirname, "src/enums")
alias["@filegen"] = path.resolve(__dirname, "src/filegen")
alias["@src"] = path.resolve(__dirname, "src")
alias["@entities"] = path.resolve(__dirname, "src/entities")
alias["@utils"] = path.resolve(__dirname, "src/utils")
const common_config = {
  mode: process.env.NODE_ENV || "development",
  devServer: {
    hot: true,
    historyApiFallback: true,
  },
  resolve: {
    extensions: ["*", ".js", ".jsx"],
    alias,
  },
  watch: true,
}

function clientEntry() {
  const EXTENSION = ".jsx"
  return fs
    .readdirSync(CLIENT_DIR_PATH)
    .filter(f => f.endsWith(EXTENSION))
    .map(f => f.slice(0, -EXTENSION.length))
    .reduce((entry, page) => {
      entry[page] = [POLYFILL, `./src/client/pages/${page}.jsx`]
      return entry
    }, {})
}

// Client configurations
const client_config = {
  entry: clientEntry(),
  output: {
    path: path.join(__dirname, "public", "js"),
    publicPath: "/",
    filename: "[name].bundle.js",
  },
  module: {
    rules: [
      // React / Javascript Files
      {
        test: /\.jsx?$/,
        exclude: /node_modules/,
        use: {
          loader: "babel-loader",
          options: {
            presets: [
              "@babel/preset-env",
              "@babel/preset-flow",
              "@babel/preset-react",
            ],
            plugins: [
              "@babel/plugin-proposal-class-properties"
            ],
          },
        }
      },
      // CSS Files
      {
        test: /\.s?css$/,
        exclude: /node_modules/,
        use: [
          // creates style nodes from JS strings
          "style-loader",
          // translates CSS into CommonJS
          "css-loader",
          // compiles Sass to CSS, using Node Sass by default
          "sass-loader",
        ],
      },
      // Images
      {
        test: /\.(jpg|png|gif|svg|pdf|ico|txt)$/,
        exclude: /node_modules/,
        // TODO: need to watch out for images!
        use: [
          {
            loader: "file-loader",
            options: {
              name: "[hash:16].[ext]",
              outputPath: "img",
              publicPath: "public/img",
            }
          }
        ],
      },
    ],
  },
  plugins: [
    new webpack.HotModuleReplacementPlugin(),
  ],
}

// Server configurations
// This blog helped setup this:
// https://blog.jakoblind.no/ssr-webpack-bundle/
const server_config = {
  context: __dirname,
  // this source map will show where bugs happen if they happen
  devtool: "source-map",
  // importing @babel/polyfill first allows this to run
  // compile async/await functions, See
  // https://zachgoll.github.io/blog/2018/async-await/
  entry: {
    db_cli: ["@babel/polyfill", "./src/db/cli/main.js"],
    generator: ["@babel/polyfill", "./src/filegen/main.js"],
    playground: ["@babel/polyfill", "./src/playground.js"],
    server: ["@babel/polyfill", "./src/server.js"],
  },
  externals: [nodeExternals()],
  output: {
    path: path.join(__dirname, "bin"),
    publicPath: "/",
    filename: "[name].build.js",
  },
  module: {
    rules: [
      // Javascript Files
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: {
          loader: "babel-loader",
          options: {
            presets: [
              "@babel/preset-env",
              "@babel/preset-flow",
            ],
            plugins: [
              "@babel/plugin-proposal-class-properties"
            ],
          },
        }
      },
    ],
  },
  node: {
    __filename: true,
    __dirname: true,
  },
  plugins: [
    new webpack.BannerPlugin({
      banner: 'require("source-map-support").install();',
      raw: true,
      entryOnly: false
    }),
  ],
  target: "node",
  watchOptions: {
    aggregateTimeout: 500,
    ignored: [
      "**/node_modules/**",
      /node_modules/,
      /views/,
    ],
  },
}

module.exports = [
  Object.assign({}, common_config, client_config),
  Object.assign({}, common_config, server_config),
]

Running ls -1AF on ./src/client/pages:

README
add_transactions.jsx
add_transactions.scss
index.jsx
index.scss
login.jsx
login.scss
manage.jsx
manage.scss
transactions.jsx
transactions.scss