On Wed, Mar 25, 2015 at 12:06 PM, Andrea Giammarchi <[email protected]> wrote: > For consistency sake I agree, but I come from a world where browsers also > exposed unofficially APIs so that, as James mentioned already, > `Array.prototype.includes` would have returned true and never worked. > > I wonder how reliable is `CSS.supports` not just in term of syntax, but > actual usability.
You give it a full property declaration, and if the browser can parse it successfully, it returns true/false. This allows for false positives (a browser parsing a property but not actually supporting it yet), but devs (rightfully) yell and scream at browsers whenever that case (parse but no support) happens, so we do it very rarely, and only ever by accident. It's just a standardized version of the de facto standard CSS feature test of "set the property on an element, and try to read it back; if you get something, it's supported". Because it's based on an objective and reliable criteria tied to directly to actual support (successful parsing), it's reliable in practice as a feature test. This differentiates it from the old hasFeature() function, which was based on a map of feature strings to bools stored in the browser, with no connection to the actual features in question, and so was inevitably filled with lies and bitrot. ~TJ _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
