[cssom] is setting Element.style as a string specified anywhere? ElementCSSInlineStyle only has the getter

[pygy]

I'm coming at this from microsoft/TypeScript#13466 which correctly points out that there is no setter for style in the old spec for ElementCSSInlineStyle. TS stops at that, and setting HTMLElement.style is thus a type error (same for SVGElement, both inherit from the mixin).

So I went out fishing for a spec for the setter and came out empty handed. The new CSSWG spec also lacks a setter... Is there such a thing, somewhere?

[Loirooriol]

Yes, in CSSOM: https://drafts.csswg.org/cssom/#elementcssinlinestyle

interface mixin ElementCSSInlineStyle {
  [SameObject, PutForwards=cssText] readonly attribute CSSStyleDeclaration style;
};

Where PutForwards=cssText means (https://heycam.github.io/webidl/#PutForwards)

If the [PutForwards] extended attribute appears on a read only regular attribute declaration whose type is an interface type, it indicates that assigning to the attribute will have specific behavior. Namely, the assignment is “forwarded” to the attribute (specified by the extended attribute argument) on the object that is currently referenced by the attribute being assigned to.

So basically element.style = string is treated as element.style.cssText = string, and cssText has an explicit setter: https://drafts.csswg.org/cssom/#dom-cssstyledeclaration-csstext

[emilio]

Yes, [PutForwards] is what does the magic here.

[pygy]

Thanks @Loirooriol @emilio !

The fact that setting null resets the styles is thus a side effect of the fact that "null" is not a valid declaration, correct?