As for Firefox, the op has already answered his own question (Menu – Web Developer – Network or Ctrl + Shift + K – Network or Ctrl + Shift + Q), but I’d like to mention the “app.telemetry Page Speed Monitor” addon, which does not require you to open the web console first. It’ll just … Read more
Behaviour is browser depended but iOS Safari and Android Chrome will respect the media queries and only download the background images for the applicable media queries. If you want to inspect this behaviour, try loading the page with Mobitest (http://mobitest.akamai.com/) or a tethered device. If you use separate CSS files (and I’d urge you not … Read more
The question is does s.async = true have a use for dynamically inserted scripts, or are these loaded asynchronously already. The answer is they aren’t loaded asynchronously in all browsers, as explained here (thanks to Markus Olsson for the link) script-inserted scripts execute asynchronously in IE and WebKit, but synchronously in Opera and pre-4.0 Firefox. … Read more