webpack.config.js

const path = require('path');
const ExtractTextPlugin=require('extract-text-webpack-plugin');
module.exports=(env)=>{
    // console.log('env',env);
    const isProduction =env ==="production";
    const CSSExtract = new ExtractTextPlugin('styles.css');
    return {
        entry:["babel-polyfill","./src/app.js"],
        output:{
            path:path.join(__dirname,'public','dist'),
            filename:"bundle.js"
        },
        module: {
            rules: [{
                loader: 'babel-loader',
                test: /\.js$/,
                exclude: /node_modules/
            },{
                test:/\.s?css$/,
                use: CSSExtract.extract({
                    use:[
                        {
                            loader:"css-loader",
                            options:{
                                sourceMap:true
                            }
                        },
                        {
                            loader:"sass-loader",
                            options:{
                                sourceMap:true
                            }
                        }
                    ]
                })
            }]
        },
        plugins:[
            CSSExtract
        ],
        devtool:isProduction ? "source-map":"inline-source-map",
        devServer:{
            contentBase:path.join(__dirname,"public"),
            historyApiFallback:true,
            publicPath:'/dist/'
        }
    };
};