webpack.config.js

var path = require('path');
var HtmlwebpackPlugin = require('html-webpack-plugin');
var webpack = require('webpack');
var merge = require('webpack-merge');

const TARGET = process.env.npm_lifecycle_event;
const PATHS = {
    app: path.join(__dirname, 'dev'),
    build: path.join(__dirname, 'build')
};

process.env.BABEL_ENV = TARGET;

var common = {
    // Entry accepts a path of an object of entries.
    entry: PATHS.app,
    // Add resolve.exteionss '' is needed to allow imports an extension
    // Note the .'s before extensions, without those matching will fail
    resolve: {
        extensions: ['', '.js', '.jsx']
    },
    module: {
        loaders: [
            {
                test: /\.jsx?$/,
                exclude: /(node_modules)/,
                loader: 'babel', 
                query: {cacheDirectory: true, plugins: ['object-assign']},
                include: PATHS.app
            },
            {
                test: /\.(png|woff(2)?|eot|ttf|svg)(\?[a-z0-9=\.]+)?$/,
                loaders: ['url-loader?limit=100000']
            },
            {
                // Test expects a RegExp! note the slashes!
                test: /\.css$/,
                loaders: ['style', 'css'],
                // Include accepts either a path or an array of paths.
                include: PATHS.app
            }
        ]
    },
    plugins: [
        new webpack.NoErrorsPlugin(),
        new HtmlwebpackPlugin({
            title: 'Project Title',
            template: './dev/index.html',
            inject: 'body'
        })
    ]
};

if(TARGET === 'start' || !TARGET) {
    module.exports = merge(common, {
        devtool: 'eval-source-map',
        devServer: {
            historyApiFallback: true,
            hot: true,
            inline: true,
            progress: true,

            // Display only errors to reduce the amount of output.
            stats: 'errors-only',

            // Parse host and port from env so this is easy to customize.
            host: process.env.HOST,
            port: process.env.PORT
        },
        plugins: [
            new webpack.HotModuleReplacementPlugin()
        ]
    });
}

if(TARGET === 'build') {
    module.exports = merge(common, {
        output: {
            path: PATHS.build,
            filename: 'bundle.js'
        },
        devtool: 'source-map',
        plugins: [
            // Setting DefinePlugin affects React library size!
            new webpack.DefinePlugin({
                'process.env.NODE_ENV': JSON.stringify('production')
            }),
            new webpack.optimize.UglifyJsPlugin({
                compress: {
                    warnings: false
                }
            })
        ]
    });
}