Re: [csswg-drafts] [cssom] Properties that allow access to parsed-but-invalid syntactic constructs (declarations, rules, etc) as a low-fi way to make polyfills easier (#13186)

> I disagree, the polyfill author has no idea about how the standard feature will end up being, so the polyfill needs to take precedence to avoid a situation of web incompatibility.

Well, you're probably right. If the polyfill author isn't called @bramus or @mirisuzanne, we can't expect them to follow the specs closely. 😅 Plus, nobody can predict the future. So it might happen that somebody creates a completely new feature using those APIs unrelated to any standardized feature. And if that _does_ get standardized later on, it might be totally different from that feature. Or it the polyfill implements an early version of a standardized feature, which changes later on.
So in most cases it makes sense to let the polyfill take precedence.

Though I still wonder whether it makes sense to at least allow polyfill authors to _opt into_ using the built-in feature if available. I mean, if something is quite stable spec-wise and already implemented in one or two engines, it's very unlikely to change. And in those cases a polyfill would benefit from being used as a fallback.

Sebastian

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Received on Sunday, 18 January 2026 23:14:17 UTC