Googling respond.js vs css3-mediaqueries.js I’ve found Techniques For Gracefully Degrading Media Queries, a Smashing Magazine post about Lewis Nyman which talks about how to apply the graceful degradation of media queries on browsers that don’t support them (IE 8, IE 7, IE 6).

The options are:

  • Use a separate style sheet to load conditionally on old Internet Explorer versions, or separate style rules to apply based on the body class
  • Use a javascript fallback (using respond.js or css3-mediaqueries.js)

In case of javascript fallback, the best may be respond.js, in the following case:

  • Desktop support is a primary high concern;
  • You are querying only the width and height of the browser;
  • You don’t want to query the width by ems;
  • You have no problem with non-JavaScript users seeing an unoptimized page

In my opinion, this is a very frequent case!

CSS3-mediaqueries.js is indicated only if you have particular conditions to query (other than width and height), but it weights 15 freaking kilobytes!

So you should use respond.js and switch to css3-mediaqueries.js only if the first doesn’t fit your needs.

That’s it!