Can't use serve with Cordova / Phonegap helloworld
I know it is an old thread, but I had the same issue today and don't really want to install an emulator
you need to add the browser platform to you app
cordova platform add browser
and point your browser to http://localhost:8000/browser/www/
When you're initially prompted with the javascript dialog boxes (e.g. gap: ["PluginManager",...]) you can press Cancel to get the app to load correctly.
After discussions on IRC with a Cordova developer, the serve command is somehow not well documented and it is mostly useful to serve content to the Phonegap App Developer mobile app that was released recently, and as far as I understand it now, it is now intented to serve the application for a regular desktop browser.
For desktop browser testing, I have been succesful until now with the Ripple emulator (not the Chrome plugin which seems unmaintened, but the NPM package).
For exemple you can test in the browser phonegap apps with:
npm install -g ripple-emulator
ripple emulate
This may help you: https://github.com/stample/gulp-browserify-react-phonegap-starter