[jervisfm]

> The only thing missing is a way to edit the JS and see the result.

If you look on at the right edge of the grey-ish tab bar, you will see an "edit" link. This opens up a link to CodePen which lets you fork the snippet and mark changes to it. Here is one such link: http://codepen.io/kangax/pen/wDuxl

[sonier]

Wow, somehow I completely missed that. Thanks for pointing it out.