Earlier in the article, I alluded to the challenge of degrading the img tag gracefully in unsupported browsers. This was another problem in creating Picturefill 2.0. Because it is a polyfill, the concept of unsupported browsers doesn’t really exist (kind of) — we’re using JavaScript to force it to work.

The edge case is this: If a browser doesn’t natively support picture or srcset and has JavaScript turned off, then you’ll get a frowny face. I can already feel your eyes rolling, but knowing the limitations of a system is important before you rely on it on a large scale. If a user were to come across a Picturefill’ed image in an unsupported browser with JavaScript turned off, they would see the image’s alt text — a nice little way to reinforce the importance of descriptive and meaningful alt text, isn’t it?

Alternative text is the fallback because the previous

We’ve come a long way with responsive images. We can see the light at the end of the tunnel, but a lot of work still has to be done. And we’d love your help!
How To Get Involved.

If you’d like to get involved and help out with the responsive-images movement, join the RICG via the W3C. If that’s too much, we’re always looking for people to try out Picturefill’s beta version and submit bugs through the issue tracker on GitHub.
You can also spread the word about great tools like Sizer Soze, which calculates the performance cost of not using responsive images.

The most commonly requested yet least effective are preflight usability checks. A pre-flight evaluation is effective if the main concept is already tested and proven. Test the design before going live to reveal the last few bugs or typos that might have been overlooked.

If this is the first test on the project, it will probably reveal deeper issues. Much deeper than an easy to fix button miss-alignment or a typo.We’ve conducted quite a few preflight usability studies and many times we discovered a core problem. On one occasion, the registration steps hadn’t been ordered in a sequence that had been logical to the user. On another, the touch-screen equivalent to drag ‘n’ drop with a mouse was missing.

Fixing a broken experience that’s discovered only a day or two before launch is usually postponed until the next release. Many more times still, there’s no clear roadmap after the project delivery, so the issue is never repaired. The solution? Test your designs early.

With both picture and srcset HTML syntaxes seeming like too much effort in the wrong places, we looked for a simpler solution. We wanted to be able to add a single image path and let the CSS, JavaScript and PHP deal with serving the correct image — instead of the HTML, which should simply have the correct information in place.

At the time of developing the website, no obvious solution matched our requirements. Most centered on emulating picture or srcset, which we had already determined weren’t right for our needs.

The Etch website is very image-heavy, which would make manually resizing each image a lengthy process and prone to human error. Even running an automated Photoshop script was deemed to require too much maintenance.
Our solution was to find the display width of the image with JavaScript at page-loading time, and then pass the src and width to a PHP script, which would resize and cache the images on the fly before inserting them back into the DOM.

We’ll look at an abstracted example of the code, written in HTML, JavaScript, PHP and LESS. You can find a working demo on my website. If you’d like to grab the files for the demo, they can be found on GitHub.