Genius solution to detect @font-face feature

Paul Irish posted on his blog a beautiful solution on how to detect if @font-face is supported by the browser or not.
Here is his code:
/*!
* isFontFaceSupported - v0.3 - 8/20/2009
*
* Copyright (c) 2009 Paul Irish
* MIT license
*/

function isFontFaceSupported(){

// IE supports EOT.
// It has had EOT since IE 5.
// So we sniff. :(
if (!(!/*@cc_on@if(@_jscript_version>=5)!@end@*/0)) return true;

var doc = document,
b = doc.body,
st = doc.createElement('style'),
spn = doc.createElement('span'),
wid, nwid;

st.textContent = "@font-face{font-family:testfont;src:url('data:font/ttf;base64,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')}";

spn.setAttribute('style','font-family:monospace;position:absolute;top:-9999px;left:-9999px;visibility:hidden');

// the data-uri'd font only has the . glyph.
spn.innerHTML = '........';
spn.id = 'fonttest';

b.appendChild(st);
b.appendChild(spn);

wid = spn.offsetWidth;
spn.style.fontFamily = 'testfont,monospace';
nwid = spn.offsetWidth;

b.removeChild(st);
b.removeChild(spn);

return (isFontFaceSupported = function(){ return wid !== nwid; })();
}
You can read his entire post here
It basically creates a font with one glyph which is the "." period character and checks it’s width, sort of like what the fontAvailable jQuery plugin would do which I talked about in previous posts. Except that his technique loads a font glyph on the fly which saves requests to the server and in download size.
My solution to place a font for unsupported browsers remains the same as I have mentioned in my previous post.
Font = {
/*!
* isFontFaceSupported - v0.3 - 8/20/2009
*
* Copyright (c) 2009 Paul Irish
* MIT license
*/
isFontFaceSupported: function() {
// IE supports EOT.
// It has had EOT since IE 5.
// So we sniff. :(
if (!(!/*@cc_on@if(@_jscript_version>=5)!@end@*/0)) return true;

var doc = document,
b = doc.body,
st = doc.createElement('style'),
spn = doc.createElement('span'),
wid, nwid;

st.textContent = "@font-face{font-family:testfont;src:url('data:font/ttf;base64,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')}";

spn.setAttribute('style','font-family:monospace;position:absolute;top:-9999px;left:-9999px;visibility:hidden');

// the data-uri'd font only has the . glyph.
spn.innerHTML = '........';
spn.id = 'fonttest';

b.appendChild(st);
b.appendChild(spn);

wid = spn.offsetWidth;
spn.style.fontFamily = 'testfont,monospace';
nwid = spn.offsetWidth;

b.removeChild(st);
b.removeChild(spn);

return (isFontFaceSupported = function(){ return wid !== nwid; })();
},

// flag to tell if the font is already loaded
// remember that if the font is IE then the Cufon library
// has already been loaded.
// Also check with the jQuery Plug-In just in case.
loaded: typeof Cufon === 'function',

load: function(callback) {
$.getScript('js/lib/cufon/font.min.js', function() {
Font.loaded = true;
callback();
});
},

place: function(elem) {
// If font is already loaded via @font-face,
// then no further work is needed
if ( Font.isFontFaceSupported )
return;

function _place() {
if ( typeof elem === 'string' )
Cufon.replace(elem);
else
for ( var i in elem ) {
Cufon.replace(elem);
}

Cufon.refresh();
}

if ( !Font.loaded ) Font.load(_place);

else _place();
},

refresh: function() {
// If font is already loaded via @font-face,
// then no further work is needed
if ( Font.isFontFaceSupported )
return;

Cufon.refresh();
}
};

// Usage Example

// Hook up Cufon if font is not available
Font.place('h1');

// Replace the content of the element
$('h1').eq(0).text('A New Header Text');

// Refresh the font replacements if font is not available
Font.refresh();
It should save me a few KB by not needing the fontAvailable plugin anymore, and performance wise because it’s using native JavaScript functions.
I have not tested this new technique myself — I trust that his code work, I was talking about my updated code — as I’m not really working on it, so if it’s wrong…