screensize.js

/*
* see http://krijnhoetmer.nl/stuff/javascript/media-queries/
*/
var App = App || {};

(function(){
  var screenSizeTest = function(mediaQuery){
    return window.matchMedia(mediaQuery).matches;
  }

  var readSize = function() {    
    var pseudo = window.getComputedStyle(document.documentElement, ':before').getPropertyValue('content');
    return pseudo ? pseudo.replace(/['"]/g, '') : false;
  }

  App.isSmallScreen = function() {
    return parseInt(readSize()) === 1;
  }

  App.isMediumScreen = function() {
    return parseInt(readSize()) === 2;
  }

  App.isLargeScreen = function() {
    return parseInt(readSize()) === 3;
  }

  App.isXLargeScreen = function() {
    return parseInt(readSize()) === 4;
  }

  /*
  * Unfortunatly...
  */
  App.isSmallerThanPortraitIpad = function() {
    return screenSizeTest("(max-width: 768px)");
  }
})();