(MSIE|(?!Gecko.+)Firefox|(?!AppleWebKit.+Chrome.+)Safari|(?!AppleWebKit.+)Chrome|AppleWebKit(?!.+Chrome|.+Safari)|Gecko(?!.+Firefox))(?: |\/)([\d\.apre]+)
This regular expression is capable of retrieving the browser and version for the following browsers;
- Internet Explorer
- Firefox (INCLUDING alpha and "pre" versions)
- Other browsers reporting a "Gecko" version in their user agent
- Chrome
- Safari
- Other browsers reporting an "AppleWebKit" version in their user agent