Devil&#x27;s advocate:<p>Detecting the features available in the browser is potentially two requests: the server sends HTML&#x2F;JS to the client, the client makes a decision, and then requests more data that&#x27;s compatible with its feature set. If the server can do feature detection by user agent sniffing, it&#x27;s potentially one request.<p>The client has to do this for every browser session, too, since browsers are frequently upgraded and the features change week-to-week.