webpack.config.js

const HtmlWebpackPlugin = require('html-webpack-plugin');
const path = require('path');

module.exports = {
    module: {
        rules: [
            {
                test: /\.(js|jsx|cjs|mjs)$/, // if a file name ends with any of these strings
                exclude: /node_modules/, // don't apply these rules to anything in the node_modules folder
                use: [
                    {
                        loader: 'babel-loader', // use the babel-loader to transpile these files to javascript that the browser can understand
                        options: {
                            presets: [['@babel/preset-env'], ['@babel/preset-react'], ['@babel/preset-typescript']],
                        },
                    },
                ],
            },
            {
                test: /\.(sa|sc|c)ss$/, // if a file name ends with sass, css or scss
                use: ['style-loader', 'css-loader'],
            },
        ],
    },
    entry: './client/index.js', // starts the entrypoint of creating the dependency tree with this file
    output: {
        path: path.resolve(__dirname, 'client/build'), // outputs the bundle.js file into the build folder (which it also builds) at the specified filepath
        filename: 'bundle.js',
    },
    devServer: { // creates a development server
        static: {
            directory: path.join(__dirname, 'client'), // uses all code from the client folder to make bundle and render dev server
        },
        proxy: {
            '/api': { // whenever we make an http request to the path /api, it redirects it from 8080 to 3000 to go to the backend automatically
                target: 'http://localhost:3000',
                pathRewrite: { '^/user': '/user' },
            },
        },
        compress: true,
        port: 8090,
        // For React Router refreshing
        historyApiFallback: true,
    },
    plugins: [
        new HtmlWebpackPlugin({
            template: './client/static/index.html',
        }),
    ],
    mode: process.env.NODE_ENV, // variable that will store whether we are using dev or prod server
};