A helper class to parse the user agent string for basic info.

Browser.dart

/**
* ## Parse the user agent and retrieves information about the browser. ##
* This is a singleton class, so multiple "new Browser()" calls
* will always return the same object.
*
* ## Will attempt to provide the following: ##
* * Browser Type (Chrome, Firefox, ...)
* * Platform (Mobile, Desktop, Tablet)
* * Mobile Type (iPhone, Android, ...)
* * Major Version
*/
class Browser
{
  //Browser Type
  static final String DARTIUM = "Dartium";
  static final String CHROME = "Chrome";
  static final String FIREFOX = "Firefox";
  static final String IE = "IE";
  static final String OPERA = "Opera";
  static final String ANDROID = "Android";
  static final String SAFARI = "Safari";
  static final String LYNX = "Lynx";
  
  //Platform Type
  static final String MOBILE = "Mobile";
  static final String DESKTOP = "Desktop";
  static final String TABLET = "Tablet";
  
  
  //Mobile Type
  // ANDROID is used again for Android
  static final String IPHONE = "iPhone";
  static final String IPAD = "iPad";
  static final String WINDOWSPHONE = "Windows Phone";
    
  static final String UNKNOWN = "Unknown"; 
  
  final ua;
  
  num version;
  String browser;
  String platform;
  String mobileType;
  
  static Browser _ref;
  
  factory Browser(){
    if (_ref != null) return _ref;
    
    _ref = new Browser._internal();
    return _ref;
  }
  
  Browser._internal()
  :
    ua = window.navigator.userAgent
  {
    browser = _setBrowserType();
    platform = _setPlatform();
    mobileType = _setMobileType();
    version = _getVersion();
  }
  
  num _getVersion(){
    
    num getMajor(String ver){
      if (ver.contains('.')){
        return Math.parseInt(ver.substring(0, ver.indexOf('.')));
      }else{
        return Math.parseInt(ver);
      }
    }
    
    switch(browser){
      case DARTIUM:
      case CHROME:
        final s = ua.indexOf('Chrome/') + 7;
        final e = ua.indexOf(' ', s);
        return getMajor(ua.substring(s, e));
      case ANDROID:
        final s = ua.indexOf('Android ') + 8;
        final e = ua.indexOf(' ', s);
        return getMajor(ua.substring(s, e));
      case FIREFOX:
        final s = ua.indexOf('Firefox/') + 8;
        final e = ua.indexOf(' ', s);
        return getMajor(ua.substring(s, e));
    }
    
    return 0;
  }
  
  String _setMobileType(){
    if (platform == UNKNOWN || platform == DESKTOP){
      return UNKNOWN;
    }
    
    switch(browser){
      case CHROME:
      case ANDROID:
        return ANDROID;
      case SAFARI:
        if (ua.contains('iPhone') || ua.contains('iPod')){
          return IPHONE;
        }
        
        if (ua.contains('iPad')){
          return IPAD;
        }
        
        return UNKNOWN;
      case IE:
        //TODO: "Surface" tablet
        return WINDOWSPHONE;
      case OPERA:
        if (ua.contains('Android')){
          return ANDROID;
        }
        if (ua.contains('iPhone')){
          return IPHONE;
        }
        if (ua.contains('iPad')){
          return IPAD;
        }
        if (ua.contains('Windows Mobile')){
          return WINDOWSPHONE;
        }
        
        return DESKTOP;
    }
    
    return UNKNOWN;
  }
  
  String _setPlatform(){
    if (browser == UNKNOWN) return UNKNOWN;
    
    switch(browser){
      case DARTIUM:
        return DESKTOP;
      case ANDROID:
        return MOBILE;
      case CHROME:
        if (ua.contains('<Android Version>')){
          return (ua.contains('Mobile') ? MOBILE : TABLET);
        }
        return DESKTOP;
      case SAFARI:
        if (ua.contains('iPhone') || ua.contains('iPod')){
          return MOBILE;
        }
        
        if (ua.contains('iPad')){
          return TABLET;
        }
        
        return DESKTOP;
      case IE:
        if (ua.contains('Windows Phone')){
          return MOBILE;
        }
        
        //TODO: need UA for "Surface" tablet eventually
        
        return DESKTOP;
      case OPERA:
        if (ua.contains('Opera Tablet')){
          return TABLET;
        }
        if (ua.contains('Mini') || ua.contains('Mobile')){
          return MOBILE;
        }
        return DESKTOP;
    }
    
    return UNKNOWN;
  }
  
  String _setBrowserType(){
    
    //source: http://www.zytrax.com/tech/web/browser_ids.htm
    if (ua.contains('(Dart)')) return DARTIUM;
    if (ua.contains('Chrome/')) return CHROME;
    if (ua.contains('Firefox/') || ua.contains('ThunderBrowse')) return FIREFOX;
    if (ua.contains('MSIE')) return IE;
    if (ua.contains('Opera')) return OPERA;
    if (ua.contains('Android')) return ANDROID;
    if (ua.contains('Safari')) return SAFARI;
    if (ua.contains('Lynx')) return LYNX;

    return UNKNOWN;
  }
  
  String toString() => "Browser Info (Type: ${browser}, Version: ${version}, Platform: ${platform}, MobileType: ${mobileType})";
}