In short, here is the jsfiddle link.
In recent article on moztech (in Chinese) I've introduce ghapplate to develop and host web app directly on github. After the post is published, I'm still seeking for a more easier approach. Since github does not provide web preview while editing, you have to save your current work then view it later on browser to see if it's the expect result.
So jsfiddle comes to my mind. Here is a playground that preload the libraries used by ghapplate and webapplate.
It's possible to use jsfiddle to prototype web app as well. What you need is attach `/manifest.webapp` postfix after your jsfiddle link.
jsfiddle and ghapplate are good for quick experiment. If you want to get benefit from optimizer, lint check and more during serious web development, webapplate is still the more maintainable choice.