Re: [css-houdini-drafts] [css-typed-om] Provide a way to resolve a CSSUnitValue and CSSMath* to a pixel value

(I'm using `to()` here, rather than the method shape you suggested, because we need to resolve it into some specific unit. We don't have a type that represents a nebulous "length, in some unspecified unit" type, which is the only thing we could reasonably return from such a conversion function.)

That said! I think we might want to allow something that, for example, keeps %s as they are while resolving the rest into a length as much as possible. This is useful for cases like `background-position`, where the % doesn't resolve into a length in a straightforward way. I think we can handle all the use-cases for this by just adding this options bag to `toSum()` as well; if a % doesn't trivially resolve into a length, then it can't be used in a `px / %` expression anyway, so requiring that it resolve into a sum should be fine.

In other words, calling `len.toSum("px", "percent", {element:el})` should be able to *always* succeed, and will always return a `CSSMathSum` where the first element is a `CSS.px()` and the second is a `CSS.percent()`.

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Received on Thursday, 23 August 2018 20:44:34 UTC