Gruntfile.js

module.exports = function(grunt) {

    var webpack = require("webpack");
    var webpackConfig = require("./webpack.config.js");

    require("matchdep").filterAll("grunt-*").forEach(
        grunt.loadNpmTasks);

    grunt.loadNpmTasks('grunt-webpack');

    webpackConfig.output.filename = "bundle.min.js";

    grunt.initConfig({

        webpack: {
            options: webpackConfig,
            build: {

                plugins: webpackConfig.plugins.concat(
                    new webpack.DefinePlugin({
                        "process.env": {
                            // This has effect on the react lib size
                            "NODE_ENV": JSON.stringify("production")
                        }
                    }),
                    new webpack.optimize.DedupePlugin(),
                    new webpack.optimize.UglifyJsPlugin()
                )
            },
            "build-dev": {
                devtool: "sourcemap",
                debug: true
            }
        },
        "webpack-dev-server": {
            options: {
                webpack: webpackConfig,
                publicPath: "/" + webpackConfig.output.publicPath
            },
            start: {
                keepAlive: true,
                webpack: {
                    devtool: "eval",
                    debug: true
                }
            }
        },
        watch: {
            app: {
                files: ["app/**/*", "web_modules/**/*"],
                tasks: ["webpack:build-dev"],
                options: {
                    spawn: false
                }
            }
        }
    });

    // The development server (the recommended option for development)
    grunt.registerTask("default", ["webpack-dev-server:start"]);

    // Build and watch cycle (another option for development)
    // Advantage: No server required, can run app from filesystem
    // Disadvantage: Requests are not blocked until bundle is available,
    //               can serve an old app on too fast refresh
    grunt.registerTask("dev", ["webpack:build-dev", "watch:app"]);

    // Production build
    grunt.registerTask("build", ["webpack:build"]);
};