classList property of elements is not populated

[amb26]

I can see that there is a placeholder for this since the property is attached but it is always populated with a Set of 0 elements, regardless of whether there is a "class" attribute on the element or not.

Specified in the DOM API here: https://developer.mozilla.org/en-US/docs/Web/API/Element/classList

See attached image showing classList as Set(0) even though there is an class attribute holding value renderer-test-container

[amb26]

"By eye" I see (at least) two sources of leakage -
i) The classList Set is not updated when markup is cloned via node.cloneNode()
ii) The classList is not updated if an existing "class" attribute is updated - e.g. at https://github.com/WebReflection/linkedom/blob/main/cjs/interface/element.js#L270

The following workaround is necessary before any read of classList:

        var clazz = node.getAttribute("class");
        node.removeAttribute("class");
        node.setAttribute("class", clazz);  

Note that being implemented in terms of a Set, the classList does not perfectly conform to the DOM API describing a "DOMTokenList" - e.g. it is missing a "length" property. Given that the developer has said that the target is only for linkedom to be "close" to the DOM API this may not be terribly important, since I guess it is still usable in spread contexts and via a few of its advertised named methods, but I think it should be kept in sync with the value imputed by "class".

[WebReflection]

Why do you use getAttribute and setAttribute or removeAttribute for class, if I might ask? You have element.className accessor and the classList too, and the `classList is lazy. Do you have any use case for this? I don't find this particularly interesting and using either ways (accessor or classList) reflect already in the attribute. Making attribute reflect on classList adds complexity for I am not sure what gain.

[WebReflection]

@amb26 never mind ... I think I've found a decent compromise to make it work. Fixed, thanks.