webpack.config.js

const path = require('path');
const webpack = require('webpack');
const CopyWebpackPlugin = require('copy-webpack-plugin');

module.exports = {
  entry: {
   app: './src/index.js'
  },
  output: {
    filename: 'main.js',
    path: path.resolve(__dirname, 'build'),
  },
  devServer: {
    contentBase: path.resolve(__dirname, 'build'),
  },
  plugins: [
    new CopyWebpackPlugin([
    {
      from: path.resolve(__dirname, 'index.html'),
      to: path.resolve(__dirname, 'build')
    },
    {
      from: path.resolve(__dirname, 'assets', '**', '*'),
      to: path.resolve(__dirname, 'build')
    }
  ]),
    new webpack.DefinePlugin({
      'typeof CANVAS_RENDERER': JSON.stringify(true),
      'typeof WEBGL_RENDERER': JSON.stringify(true)
    })
  ],
  module: {
    rules: [
      {
        test: /\.js$/,
        include: path.resolve(__dirname, 'src/'),
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env']
          }
        }
      }
    ]
  }
};