Just for you, I went through their source, and these are all the jquery specific calls -

.height() .width() .offset() .remove() .append() .prepend() .prependTo() .find() .parent() .on() .off() .scrollTop() .outerHeight() .length

It seems to me like all of these would be covered by zepto. Or qwery. Or you could make your own adapter with Prototype. Or Mootools. Or Ext. Or YUI. Heck, you could probably whip up your own little library based on sizzle, or even just querySelectorAll. Then just fork infinity to use your lib, and you're good to go.

I hope you're not confused any more!

[I'm not affiliated with airbnb, just thought I'd help you out]

ok, sounds like a lot of boilerplate code to write, because "Its only dependency is on jQuery."

<script src="zepto.js"></script> <script> var jQuery = Zepto; </script> <script src="infinity.js"></script>

There.