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)

It's good to remember that there are several types of polyfill. Some (like element queries in 2011) roll out years before the a feature is stable or even in progress. For those, the goal is to have access to the feature before it is available in browsers – with an understanding that the feature might change dramatically. Others (like OddBirds recent ones) might actually be developed and released alongside browser implementations, staying up to date with changes in the spec. In that case the goal is less about early access to an unstable feature, and more about backwards compatibility for a stable feature. Because people want to use something _newly Baseline_ without waiting 2.5 years for it to become _widely available_. (Or you have a longer support tail than Baseline assumes)

For one of those, you want a polyfill priority. For the other, you explicitly want feature priority. The polyfill is only ever intended as a fallback. And that is a distinction that the polyfill author has some knowledge about.

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Received on Monday, 19 January 2026 18:12:23 UTC