hacks.mozilla.org

In today’s feature post we’ll talk briefly about three new CSS3 pseudo-classes: only-of-type, first-of-type and last-of-type. These are all very similar to the *-nth classes we covered in an earlier post.

first-of-type and last-of-type

These two pseudo-classes allow you to select the first and last item in a list of siblings within a particular element. You can use this to color the first item in a list, use opacity to make the last paragraph on a page fade out or a number of other things. Here’s an example that sets small caps on the first paragraph of a document:

#type-ex1 div:first-of-type {
    font-variant: small-caps;
}

only-of-type

only-of-type is similar to the previous two, but only selects an element if it has no siblings with the same name. Here’s a somewhat contrived example* that will hide single images inside of a div. If there’s more than one image in the div they will be visible:

.type-ex2 img:only-of-type {
    display: none;
}

And that’s it. Enjoy!

[ * Note: if someone can come up with a better example for only-of-type I'm all ears. There are very few examples of where this is useful. ]

Today’s demo comes to us from Samuel Goldszmidt. He’s a web developer specializing in audio applications at Institut de Recherche et Coordination Acoustique/Musique (IRCAM). IRCAM is a European institute covering science, sound and avant garde electro-acoustical art music.

The demo uses XML to describe the various segments of a piece of music – Florence Baschet’s StreicherKreis (Circle of Strings). The music itself is a combination of stringed instruments and electronic effects. From the XML, SVG is generated for each section of the music. You can click on each section to listen to that part of the piece and a description is shown on how that particular section was created.

As far as demos go, this is relatively simple. But it’s worth highlighting because it shows how easy it is to build a timeline around a piece of music and add descriptive information. In this case, it’s information meant to teach people how a particular effect was created. But it could be anything, from showing different camera angles of people playing the music to links about different covers of a popular piece. Opening up media to the web means that we can combine it with text, images and other media. This is just a small example.

View the Demo in Firefox 3.5

Today we released Firefox 3.5, which as we said at the beginning of the 35 days project is a huge upgrade for both end users but also for the web.

In the past we’ve always published a list of web developer features for a release. But the feature list for developers for 3.5 is so long that we thought it might be useful to try and break it down into easy-to-swallow bites. And my suspicion, given the number of comments and the number of daily views this weblog gets, is that it’s actually been useful to people.

We’ve been writing articles on features to get people informed on what the changes are, but we’ve also been featuring demos to get people inspired. Some of them have been built by people at the Mozilla core, but the really great thing that we’ve seen is that people have started to show up and build demos for our project without us having to ask. I think that this points to the fact that people are really bullish on the future of the web. People want to see change, they want to see improvements and they understand that every individual has a role to play in that. To everyone involved, I say thank you. You’re helping to improve the web, one action at a time.

We’re about half way through our 35 days posts and we will continue to make posts. And we’re still looking for help. If you want to get involved, you’re more than welcome to join us. There’s always something that you can do – follow our twitter account, write a demo, document a feature or, really, just start using this stuff. We’re helping to write the future of the web and everyone has a part to play.