Detecting Firefox and thanking users

firefoxdetect.js

(function(){
var messages = {

  'Firefox': ''+
    '<h2>Thanks for using Firefox!</h2>'+
    '<img src="http://misfitgeek.com/images/firefox3.jpeg" alt="Firefox">',

  'FirefoxAndroid': ''+
    '<h2>Thanks for using Firefox for Android!</h2>'+
    '<img src="http://misfitgeek.com/images/fennec-icon.jpeg" '+
    '     alt="Firefox Mobile">',

  'Android': ''+
    '<h2>Get Firefox Mobile!</h2>'+
    '<a href="http://www.mozilla.org/en-US/mobile/">'+
    '<img src="http://misfitgeek.com/images/fennec-icon.jpeg" '+  
    '      alt="Firefox Mobile"></a>'+
    '<strong>Click the Tail & Get Firefox Mobile for Android!</strong>',
  
  'NonAndroid': ''+
    '<h2>Please consider using Firefox!</h2>' +
    '<a title="Get FireFox !" href="http://getfirefox.org/">'+
    '<img src="http://misfitgeek.com/static/getfirefox.png" '+
    '     alt="Get Firefox">'+
    '</a>'
    
};
var out = '';
var isAndroid = navigator.userAgent.toLowerCase().indexOf("android") > 0;
var isFirefox = typeof window.mozPaintCount === 'number';
if (isFirefox) { out = messages['Firefox']; } 
if (isFirefox && isAndroid) { out = messages['FirefoxAndroid']; }
if (!isFirefox && isAndroid) { out = messages['Android']; }
if (!isFirefox && !isAndroid) { out = messages['NonAndroid']; }
var msg = document.createElement('div');
msg.innerHTML = out;
var me = document.getElementById('firefoxtest');
me.parentNode.replaceChild(msg, me);
})();