Actionscript Cookbook

1.8. Creating Reusable Code

Problem

You want to perform a series of actions at various times without duplicating code unnecessarily throughout your movie.

Solution

Create a function and then call (i.e., invoke) it by name whenever you need to execute those actions.

There is more than one way to create (i.e., define or declare) a function. Here is how to create a named function:

function functionName (  ) {
  // Statements go here.
}

To call (i.e., execute) the named function, refer to it by name, such as:

                  functionName(  );

Here is how to create a function literal:

                  functionName = function (  ) {
  // Statements go here.
};

Although not strictly required, it is considered a best practice to include a semicolon following the closing curly brace when defining a function literal.

Discussion

Grouping statements into a function allows you to define the function once but execute it as many times as you’d like. This is useful when you need to perform similar actions at various times without duplicating the same code in multiple places. Keeping your code centralized in functions makes it easier to understand (because you can write the function once and then ignore the details when using it) and easier to maintain (because you can make changes in one place rather than in multiple places).

There are two common ways of defining ActionScript functions: as named functions or function literals (a.k.a. anonymous functions). Each of these ways of declaring a function has its own use.

The named function declaration ...