webpack.config.js

const path = require("path");
const HtmlWebPackPlugin = require("html-webpack-plugin");

module.exports = {
  entry: path.join(__dirname, "src", "index.js"),
  output: {
    path: path.join(__dirname, "build"),
    filename: "index.bundle.js"
  },
  mode: process.env.NODE_ENV || "development",
  resolve: {
    modules: [path.resolve(__dirname, "src"), "node_modules"]
  },
  devServer: {
    contentBase: path.join(__dirname, "src")
  },
  module: {
    rules: [
      {
        test: /\.(js)$/,
        exclude: /node_modules/,
        use: {
          loader: "babel-loader"
        }
      },
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: ["babel-loader", "eslint-loader"]
      },
      {
        test: /\.(css|scss)$/,
        use: [
          "style-loader", // creates style nodes from JS strings
          "css-loader", // translates CSS into CommonJS
          "sass-loader" // compiles Sass to CSS, using Node Sass by default
        ]
      },
      {
        test: /\.(jpg|jpeg|png|gif|mp3|svg)$/,
        loaders: ["file-loader"]
      },
      {
        test: /\.html$/,
        use: [
          {
            loader: "html-loader"
          }
        ]
      }
    ]
  },
  plugins: [
    new HtmlWebPackPlugin({
      template: "./src/index.html",
      filename: "./index.html"
    })
  ],
  watchOptions: {
    aggregateTimeout: 300,
    poll: 1000
  }
};