jQuery Font Detection.js

/*
jQuery Font Detection Plugin by Kyle Slattery (http://kyleslattery.com)

Used to determine if a font is installed on a user's computer
Inspired by: http://remysharp.com/2008/07/08/how-to-detect-if-a-font-is-installed-only-using-javascript/

Use:
  if($.fontInstalled('Helvetica')) {
    // font is installed
  } else {
    // font is not installed
  }
*/

$.fontInstalled = function(font) {
  var test_string = 'mmmmmmmmmwwwwwww';
  var test_font = '"Courier New", monospace';
    
  var testbed = $('<div></div>').css({position: 'absolute', left: '-9999px', visibility: 'hidden'});
  var control = $('<span></span>').text(test_string).css({fontSize: '50px', fontFamily: test_font}).appendTo(testbed);
  var tester  = $('<span></span>').text(test_string).css({fontSize: '50px', fontFamily: font + ', ' + test_font}).appendTo(testbed);
  
  testbed.appendTo('body');
  var installed = (control.width() != tester.width())
  
  testbed.remove();
  return installed;
}