webpack.config.js

var webpack = require('webpack');
var ExtractTextPlugin = require("extract-text-webpack-plugin");
var path = require("path");
var UglifyJsPlugin = require('uglifyjs-webpack-plugin');
var glob = require('glob');
let PurifyCSSPlugin = require('purifycss-webpack');
var HtmlWebpackPlugin = require('html-webpack-plugin');
var CleanWebpackPlugin = require('clean-webpack-plugin')


var inProduction = (process.env.NODE_ENV === 'production');

var HWPConfig = new HtmlWebpackPlugin({
    template: __dirname + "/index.html",
    file: "index.html",
    inject: "body"
});

module.exports = {
    entry: {
        app: [
            './src/main.js',
            './src/main.scss'
        ]
    },
    output: {
        path: path.resolve(__dirname, './dist'),
        filename: '[name].[chunkhash].js'
    },
    module: {
        rules: [{
                test: /\.s[ac]ss$/,
                use: ExtractTextPlugin.extract({
                    use: ['css-loader', 'sass-loader'],
                    fallback: 'style-loader'
                })
            },
            {
                test: /\.(png|jpg|gif|svg|eot|ttf|woff|woff2)$/,
                loader: 'file-loader',
                options: {
                    name: 'img/[name].[hash].[ext]'
                }
            },
            {
                test: /\.js$/,
                exclude: /node_modules/,
                loader: "babel-loader",
                query: {
                    presets: [
                        ["es2015", {
                            modules: false
                        }]
                    ]
                }
            },
        ]
    },
    plugins: [
        HWPConfig,
        new CleanWebpackPlugin(['dist'], {
            root: __dirname,
            verbose: true,
            dry: false
        }),
        new ExtractTextPlugin('[name].css'),
        new PurifyCSSPlugin({
            paths: glob.sync(path.join(__dirname, 'index.html')),
            minimize: inProduction
        }),

        new webpack.LoaderOptionsPlugin({
            minimize: inProduction
        }),
    ]
};

if (inProduction) {
    module.exports.plugins.push(
        new UglifyJsPlugin({
            uglifyOptions: {
                compress: {
                    warnings: false
                },
                output: {
                    comments: false
                },
                sourceMap: true
            }
        })
    )
}