metafizzy/isotope ? reverse-engineered prompt

Build me a small browser library for arranging a grid of cards that can filter, sort, and reshuffle itself smoothly.

I want to be able to drop in a bunch of items, point it at the item selector, and have it lay things out in a masonry style grid. It should work when I initialize it with JavaScript, and also when I add a data attribute with options in JSON. Please include a simple demo page and clear examples for hiding and showing items, sorting them, and updating the layout without the page feeling jumpy.

Keep it easy to use in plain JavaScript, and make sure it still feels good if someone wants to plug it into an existing site. If you need to check current docs or examples online to match how this kind of library is usually used, go ahead and look them up.