// this detects if a font is installed: 
// http://www.whatstyle.net/articles/54/guessing_font_availability_with_javascript
function guessFontAvailability (desiredFont) {
// create an element with the desired font family
var a = document.createElement ('span');
a.appendChild (document.createTextNode ('AAA'));
a.style.fontFamily = desiredFont + ', monospace';
a.style.fontSize = '100px';
a.style.visibility = 'hidden';
// create an element which will use the browser's default monospace font
var b = document.createElement ('span');
b.appendChild (document.createTextNode ('AAA'));
b.style.fontFamily = 'monospace';
b.style.fontSize = '100px';
b.style.visibility = 'hidden';
// attach the elements to the body
document.body.appendChild (a);
document.body.appendChild (b);
// check if the dimensions of the elements are similar
var available = true;
if (a.offsetWidth === b.offsetWidth &&
a.offsetHeight === b.offsetHeight) {
available = false;
}
// remove the elements and return the availability of the font
a.parentNode.removeChild (a);
b.parentNode.removeChild (b);
return available;
}

if (!guessFontAvailability ('Lucida Handwriting')) {
// if the font is not available, provide an alternative styling hook
document.body.className += ' alt-font';
}