Decide on proper API Shape

[bramus]

Now:

const cssStyleObserver = new CSSStyleObserver(
  observedVariables: string[],
  callback: CSSStyleObserverCallback
);

cssStyleObserver.attach(targetElement: HTMLElement);

But maybe it’s better that this became the following? Then you can have one observer watch multiple elements.

const cssStyleObserver = new CSSStyleObserver(
  callback: CSSStyleObserverCallback
);

cssStyleObserver.attach(
  targetElement: HTMLElement,
  observedVariables: string[]
);

If being able to observer multiple elements is the only goal, though, maybe the following is also OK?

cssStyleObserver.attach(targetElements: NodeList);

[bramus]

Furthermore, to be in line with MutationObserver, the attach method should be renamed to observe and a bunch of things should move around.

For reference:

const observer = new MutationObserver(callback);
observer.observe(target, options);

[EswaramoorthyKarthikeyan]

Can you please emit the updated element

[bramus]

The element is the one that you are observing.

[EswaramoorthyKarthikeyan]

I am observing multiple elements, and I want to know which one's style has changed so I can modify that element accordingly.

[bramus]

I see. Seems like a good addition to go add to the ReturnFormat.OBJECT return format.

Edit: I have split this off into its own issue, as this issue here is more about how to instantiate and attach the CSSStyleObserver