webpack.config.js

const path = require('path')
const HtmlWebpackPlugin = require('html-webpack-plugin')
const {CleanWebpackPlugin} = require('clean-webpack-plugin')

module.exports = {
    context: path.resolve(__dirname, 'src'),
    mode: 'development',
    entry: "./index.js",
    output: {
        path: path.join(__dirname, "build"),
        filename: 'bundle.js'
    },
    plugins: [
        new HtmlWebpackPlugin({
            template: './index.html'
        }),
        new CleanWebpackPlugin()
    ],
    module: {
        rules: [
            {
              test: /\.m?(js|jsx)$/,
              exclude: /(node_modules|bower_components)/,
              use: {
                loader: 'babel-loader',
                options: {
                  presets: ['@babel/preset-env', '@babel/preset-react'],
                  plugins: ["@babel/plugin-proposal-class-properties"]
                }
              }
            },
            {
                test: /\.css$/i,
                use: ['style-loader', 'css-loader']
            }
        ]
    }
}