webpack.config.js

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

module.exports = {
    entry: {
        app: './src/index.js'
    },
    output: {
        filename: '[name].bundle.js',
        path: path.resolve(__dirname, 'public')
    },
    module: {
        rules: [{
            test: /\.(js|jsx)$/,
            exclude: /node_modules/,
            use: {
                loader: 'babel-loader'
            }
        }]
    },
    devServer: {
        hot: true,
        allowedHosts: 'all',
    },
    plugins: [
        new webpack.HotModuleReplacementPlugin()
    ]
};