package.json

{
  "name": "nodeapp",
  "main": "server.js",
  "scripts": {
    "build": "webpack-cli"
  },
  "dependencies": {
    "express": "^4.17.1",
    "webpack": "^4.41.5"
  }
}

server.js

const e = require("express");

console.log(e);

webpack.config.js

module.exports = {
  entry: "./server.js",
  output: {
    filename: "bundle.js"
  },
  target: "node"
};