I went through the code for each, starting with the simplest and working my way up to the much more interesting and complex.
The only thing missing is a way to edit the JS and see the result. Looks like it's easy to use an embedded jsfiddle, but I have not tried it myself.
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