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Preface > Undocumented ActionScript Features

Undocumented ActionScript Features

The Flash development community has a knack for unearthing so-called undocumented features of ActionScript—internal abilities of the language that are not officially released or sanctioned for use by Macromedia. In general, use of undocumented features is not recommended because:

  • They are not tested for external use and may therefore contain bugs or be unstable.

  • They may be removed from future versions of the language without warning.

In this book, we chose to focus on providing the best possible documentation for features that are supported but which may be poorly documented or misdocumented. Therefore, wholly undocumented or unsupported features are not covered unless:

  • Macromedia sources have supplied or confirmed the information directly; or

  • Use of the feature is so widespread that it demands discussion.

In either case, descriptions in this book of undocumented features include the appropriate warning label in full view. This book covers the following undocumented features:

  • __proto__ (as used to establish inheritance)

  • ASBroadcaster (partial coverage only, in Chapter 12)

  • ASSetPropFlags( ) (partial coverage only, in Chapter 8)

  • LoadVars.decode( )

  • LoadVars.onData( )

  • Object.hasOwnProperty( )

  • System.showSettings( )

  • TextField.condenseWhite

  • TextFormat.font's multiple font abilities

  • The XMLNode class

To see what the ActionScript sleuths have discovered, visit (with prudence):

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