webpack.config.js

const path = require('path');
const webpack = require('webpack');

module.exports = {
  mode: process.env.NODE_ENV,
  entry: './client/index.js',
  output: {
    path: path.resolve(__dirname, 'build'),
    filename: 'bundle.js',
  },
  devServer: {
    publicPath: '/build',
    historyApiFallback: true,
    proxy: {
      '/api': 'http://localhost:3000',
    },
  },
  module: {
    rules: [
      {
        test: /.(js|jsx)$/,
        exclude: /(node_modules)/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env', '@babel/preset-react'],
          },
        },
      },
      {
        test: /\.s[ac]ss$/i,
        exclude: /(node_modules)/,
        use: ['style-loader', 'css-loader', 'sass-loader'],
      },
      {
        test: /\.(png|jpe?g|gif)$/i,
        use: [
          {
            loader: 'file-loader',
          },
        ],
      },
    ],
  },
  plugins: [new webpack.ProvidePlugin({ 'window.decomp': 'poly-decomp' })],
};