data-* attribute on the element, like:
<div data-anijs="if: click, do: flipInY, to: .container-box"></div>
Here's a simple example:
I mention it here, because the website for AniJS features a bunch of links to examples all over here on CodePen. We're a little biased, but we think that's a swell idea. Any newfangled front-end thing really should have a way you can not just see a demo, but play with it and give you the ability to quickly keep a copy for yourself.