Re: [csswg-drafts] [css-env-1] - Pushing data from CSS? (#4911)

> > If there were a way to push data into JavaScript land, perhaps in the form of an event or signal of some sort, then a script could handle the setting of a custom rule on a set of elements without having to watch the DOM and stylesheets for a custom property that is intended to be "JS enhanced".
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> Yes, this is planned for a future Houdini spec: letting JS process a custom property to produce a "computed value" or "used value", and/or letting JS register "property listeners" on elements that get called when a property's value changes.
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> > Another use-case could be pushing data when media queries are activated; then JS could perhaps make further responsive enhancements (as responsive design is currently the prime motivator for using media queries).
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> This can already be done! You can evaluate MQs directly in JS, and register a listener for when they change: <https://developer.mozilla.org/en-US/docs/Web/API/MediaQueryList/addListener>
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> > Some other ideas: calc could be supplemented with other functions whose implementation is in JS - however, this would be hidden to the user of the function, preserving the declarative, decorative semantics of CSS. Any function could be defined; e.g., string manipulation functions, numeric-valued functions, such as, say, grabbing the width of another element for use in a value (e.g. height: calc(width(#myDiv) + 2em)).
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> This is another planned Houdini spec: Houdini Custom Functions. ^_^

Thank you for the informative reply! Had no idea about media query listeners. 

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Received on Sunday, 5 April 2020 19:17:38 UTC