conditional-classes
I made this to experiment with and learn about container queries. If you want to use container queries in production, you should probably be using something else.
Requirements
conditional-classes.js requires ResizeObserver. ResizeObserver is shipping in Blink and coming soon to Firefox and Safari; in the meantime there’s an excellent polyfill.
Usage
Load conditional-classes.js in the <head>, after any ResizeObserver polyfill, synchronously.
<head>
<!-- (head stuff) -->
<script src="ResizeObserverPolyfill.js"></script>
<script src="conditional-classes.js"></script>
</head>Then use it like this:
.container {
--if: (300px < inline <= 600px) .medium,
(inline > 600px) .large;
}
.container.medium .element {
/* do container query stuff */
}
.container.large .element {
/* do some other container query stuff */
}Currently supports querying the inline and block content-box sizes of elements.
TODO
- Right now we check for
--ifs when elements are inserted into the DOM, and then never check for or look at them again. A better script would respond appropriately to updates to CSS & HTML.