[whatwg] RWD Heaven: if browsers reported device capabilities in a request header

[irakli]

Responsive Web Design [http://bit.ly/f6TPB7] is an extremely important
approach/technique/movement for making web mobile-friendly. Given that web
mobile traffic is exploding and there were more smart-phones sold in 2011
than PCs [http://vrge.co/wqOiED] the importance of the movement can not be
emphasized enough.

We have some significant obstacles on the path of fully optimized
Responsive Web Design, however. Responsive Images (smaller images for
smaller screens to optimize download times) and optimized CSS/JS (mobile
devices don't need the same JS/CSS as desktop browsers do) are the obvious
ones.

The most optimal way to handle responsive images and optimize CSS/JS would
be on the server-side. However, server-side does not have enough
information about device capabilities, resulting in emergence of all kinds
of cruft-y solutions (e.g. using <div>'s for <img> tags etc.) that should
not exist.

However, browsers do know a lot about devices they are running on and could
pass that information to servers as part of the initial request, making it
possible for servers to get way smarter than what we have now.

Something as simple as if browsers passed along device's width/height
information as part of the initial request headers would go a very very
long way, making it possible to make a lot of intelligent decisions on the
server-side (eventually allowing "media-queries-like" systems on the
server-side).

Since some proxy servers cut-off or disable custom headers, probably the
safest way to add this is to add width/height information in the user-agent
header.