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Summary

ActionScript 1.0 is the first version of ActionScript for Flash Player. In fact, the term ActionScript wasn't coined until the release of Flash Player 5 when ActionScript became much more like JavaScript. Before then, it was simply known as Flash Actions. Since then, a lot has changed. The scripting capabilities of the first versions of Flash Actions changed from simply providing timeline control for Flash animations to including more complicated logic and control structures as well as the ability to load in and dynamically manipulate external data.

Up until Flash Player 9, ActionScript 1.0, as well as its counterpart ActionScript 2.0, have been kept up to date with the new features added to each Flash Player release. After Flash Player 9, however, you'll find that most, if not all, of the new features will be requiring at least ActionScript 3.0. Though ActionScript 1.0 has not been abandoned and will continue be supported in future releases of Flash Player, it will not be able to benefit from the new features being introduced into the player.

Why Use ActionScript 1.0

Generally speaking you should not be using ActionScript 1.0. ActionScript 2.0 should be preferred over ActionScript 1.0, though use of ActionScript 3.0 is ideal. The only exception is when developing for devices that do not support newer versions of the Flash Player such as mobile devices that run Flash Lite 1.x. These devices require that ActionScript 1.0 be used.

Though ActionScript 1.0 is simpler to write compared to ActionScript 2.0 and ActionScript 3.0, the simple fact of the matter is that you are much more susceptible to errors with ActionScript 1.0 and figuring out where those errors occur is a lot more difficult. Error handling improved greatly with ActionScript 2.0 compile-time strict data typing, and ActionScript 3.0 went even further supporting runtime type checking and error handling.