CSS #font-face - what does "src: local('☺')" mean? - css

Question

I'm using #font-face for the first time and downloaded a font-kit from fontsquirrel
The code they recommend inserting into my CSS is:
#font-face {
font-family: 'junctionregularRegular';
src: url('Junction-webfont.eot');
src: local('☺'),
url('Junction-webfont.woff') format('woff'),
url('Junction-webfont.ttf') format('truetype'),
url('Junction-webfont.svg#webfontoNEpZXy2') format('svg');
}
Now, the smiley face thing has me stumped. But so too does the number of urls in the src - why do they recommend so many files and will they all be sent to the browser when a page is rendered? Is there any harm in removing all but the .ttf?

Answer 1

if you read the notes in font-squirrel's font-face generator, you'll see that it was a gotcha by paul irish.
Here is the excerpt from his blog post:
And.. regarding #font-face syntax
I now recommend the bulletproof smiley variation over the original bulletproof syntax.
#font-face {
font-family: 'Graublau Web';
src: url('GraublauWeb.eot');
src: local('☺'),
url('GraublauWeb.woff') format('woff'), url('GraublauWeb.ttf') format('truetype');
}
From the bulletproof post:
Yes, it's a smiley face. The OpenType spec indicates any two-byte unicode characters won't work in a font name on Mac at all, so that lessens the likelihood that someone actually released a font with such a name.
There are a few reasons why smiley is a better solution:
Webkit+Font Management software can
mess up local references, like
turning glyphs into A blocks.
On OS X, Font Management software may
alter system settings to show a
dialog when trying to access a
local() font that's accessible
outside of Library/Fonts. More detail
on my bulletproof post.
Font Explorer X is
also known to mess up other stuff in
Firefox.
Although it's unlikely, you could
reference a local() font which is
completely different than what you
think it is. (Typophile post on
different fonts, same name) At the
very least its a risk, and you're
ceding control of the type to both
the browser and host machine. This
risk may not be worth the benefit of
avoiding the font download.
These are all pretty edge case issues, but it's worth considering.

Answer 2

The local(☺︎) is a css hack to divert IE6-8 from downloading fonts it can't use (it can only use fonts in EOT format).
Explained: The last src property takes precedence in the CSS cascade, meaning that the CSS will be parsed from bottom to top. The local(☺︎) will make IE skip the src at the bottom, without wasting bandwidth downloading fonts it can't use, and rather go straight to the font in .eot format (defined on the line above in your question) that it will use. The smiley is just to ensure there won't be a local font with that name (character combination).
Read more here: http://nicewebtype.com/notes/2009/10/30/how-to-use-css-font-face/