webpack.config.js

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

module.exports = (env = {}) => {
    return {
        entry: {
            "kintone-ui-component.min": './src/js/components/index.js'
        },
        output: {
            path: path.resolve(__dirname, 'dist'),
            filename: '[name].js',
        },
        module: {
            rules: [
                {
                    test: /\.js$/,
                    exclude: /(node_modules|bower_components)/,
                    use: {
                        loader: 'babel-loader',
                        options: {
                            presets: ['react', 'stage-0', 'env'],
                            plugins: ["transform-class-properties", "transform-react-remove-prop-types"]
                        }
                    },
                },
                {
                    test: /\.css$/,
                    use: ExtractTextPlugin.extract({
                        fallback: 'style-loader',
                        use: {
                            loader: 'css-loader',
                            options: {
                                minimize: true,
                                sourceMap: true
                            }
                        }
                    })
                }
            ]
        },
        watch: env.watch,
        plugins: [
            new webpack.DefinePlugin({ // <-- key to reducing React's size
                'process.env': {
                    'NODE_ENV': JSON.stringify('production')
                }
            }),
            new webpack.optimize.UglifyJsPlugin({
                include: /\.min\.js$/,
                minimize: true
            }),
            new ExtractTextPlugin({
                filename: '[name].css'
            })
        ]
    }
}