Guides like yours (and Modernizr) are a case for browsers to make feature detection available through a Modernizr-like API.
We're having to get very, very creative to detect support for some features (e.g. writing data to an <input> and seeing if it sticks — it took a while before someone, Mike Taylor, iirc, figured that one out), and we're trusting that every new feature will be indirectly, accidentally detectable.
I'd much rather there was a standard way for a browser to say, "yep, I support this".
Guides like yours (and Modernizr) are a case for browsers to make feature detection available through a Modernizr-like API.
We're having to get very, very creative to detect support for some features (e.g. writing data to an <input> and seeing if it sticks — it took a while before someone, Mike Taylor, iirc, figured that one out), and we're trusting that every new feature will be indirectly, accidentally detectable.
I'd much rather there was a standard way for a browser to say, "yep, I support this".