Delivering content specific to device.

Hi Ben,

I don't want to go into too many details about using client hints, but what one should remember is that it is aimed at developers using database driven content. Even though the draft uses images as its examples, it is for all content, the use of images was decided on as images are the most common item people understand the differences between the different content requirements.

It does not replace the use of srcset/picture, but is meant to provide a way for server side code to get the device info required to 'decide' what content to send to the user. One of the biggest problems with device specific content is how to handle a request from the small mobile device user to show the full content that would be available to the desktop user, without the use of cookies. Using client hints, a user must only request the full desktop content by selecting it, and the site code then resends the 'headers' to specify what the user requires, cut-down mobile friendly or full content. One could use detail/summary in html, but then all the content is still delivered, and it would not take into account user preferences. It is a trade-off, and it is only meant to offer the developer a method of working with the various content requirerments, and like all things since the first iPhone, a best practice in and for its use will take time.

Naturally it suffers from the usual browser/device support problems, but most modern server installations and devices have started implementing. Full support will probably never happen, as too many small developers do not update or even care about using modern methods, (the change from mysql to pdo/mysqli is similar, or classic asp to .net).