determineFontHeight from Pixi.js

fontHeight.js

/* @license
 * pixi.js - v1.5.1
 * Copyright (c) 2012-2014, Mat Groves
 * http://goodboydigital.com/
 *
 * pixi.js is licensed under the MIT License.
 * http://www.opensource.org/licenses/mit-license.php
 *
 * http://stackoverflow.com/users/34441/ellisbben
 * great solution to the problem!
 * returns the height of the given font
 *
 * @method determineFontHeight
 * @param fontStyle {Object}
 * @private
 */
 PIXI.Text.prototype.determineFontHeight = function(fontStyle)
 {
   var result = PIXI.Text.heightCache[fontStyle];

   if (!result)
   {
     var body = document.getElementsByTagName('body')[0];
     var dummy = document.createElement('div');

     var dummyText = document.createTextNode('M');
     dummy.appendChild(dummyText);
     dummy.setAttribute('style', fontStyle + ';position:absolute;top:0;left:0');
     body.appendChild(dummy);
     result = dummy.offsetHeight;

     PIXI.Text.heightCache[fontStyle] = result;
     body.removeChild(dummy);
   }

   return result;
};