website/webpack.config.js

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

module.exports = {
    mode: 'development',
    entry: './app/static/js/index.js',
    output: {
        filename: 'main.js',
        path: path.resolve(__dirname, 'app/static/js'),
        publicPath: 'static/js'
    },
    plugins: [
        new webpack.ProvidePlugin({
           $: "jquery",
           jQuery: "jquery"
       })
    ],
    devServer: {
        proxy: {
            '/': 'http://localhost:5000'
        }
    },
    module: {
        rules: [
            {
                test: /\.js$/,
                exclude: /node_modules/,
                use: {
                    loader: 'babel-loader',
                    options: {
                        presets: ['@babel/preset-env']
                    }
                }
            }
        ]
    },
    module: {
        rules: [
            {
                test: /\.css$/,
                use: ['style-loader', 'css-loader']
            }
        ]
    }
};