ActionScript for Flash MX: The Definitive Guide, Second Edition

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Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

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Chapter 9: Functions

Once defined, we can access a function’s parameter values from inside the function

body just as we would any other variable. For example, here is a function with one

parameter:

function say (msg) { // Define the msg parameter

trace("The message is " + msg); // Use msg within the trace( ) statement

}

Our function declaration defines the parameter msg. The trace() statement uses the

msg parameter as it would any variable, in this case displaying its value to the Output

window.

Let’s use parameters with our function so that we can set the clip’s name, horizontal

distance, and vertical distance differently each time it runs. Example 9-1 shows the

revised code.

We renamed the function from moveBall( ) to the generic name moveClip( ) to reflect

its ability to work with any clip. We also defined three parameters:

theClip (the

movie clip we want to move),

xDist (the horizontal distance to move), and yDist (the

vertical distance to move). Inside the function body, we use those parameters instead

of the literal “hardcoded” values in the earlier moveBall() example, thereby allowing

our function to reposition any clip by any horizontal and vertical distance. Notice

that we no longer need the global variable

mainTimeline because the function is told

which clip to move when it