webpack.config.js

const path = require('path');
const ExtractTextPlugin = require('extract-text-webpack-plugin');

module.exports = (env) => {
    const isProduction = env === 'production';
    const CSSExtract = new ExtractTextPlugin('styles.css');

    return {
        entry: './src/app.js',
        output: {
            path:path.join(__dirname,'public','dist'),
            filename: 'bundle.js'
        },
        module: {
            rules: [{
                loader: 'babel-loader',
                test: /\.js$/,
                exclude: /node_modules/
            },{
                use: CSSExtract.extract({
                    use: [
                        {
                            loader:'css-loader',
                            options: {
                                sourceMap: true
                            }
                        },
                        {
                            loader: 'sass-loader',
                            options: {
                                sourceMap: true
                            }
                        }
                    ]
                }),
                test: /\.s?css$/,
            }]
        },
        plugins:[
            CSSExtract
        ],
        devtool: isProduction ? "source-map" : "inline-source-map",
        devServer: {
            contentBase: path.join(__dirname,'public'),
            port:9000,
            historyApiFallback: true,
            publicPath: '/dist/'
        }
    };
};