ActionScript for Flash MX: The Definitive Guide, Second Edition

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Chapter 6: Statements

var x; // Simple declaration

var x = 10; // Declaration with assignment

We’ll discuss the specific syntax of each statement throughout the rest of this chapter.

Statement Blocks

Some statements actually include other statements, or substatements, as part of their

syntax. For example, the if statement has this syntax:

if (expression) substatement;

The substatement, which is executed only if expression evaluates to true, can be a

single statement, such as a variable declaration statement:

if (x = = 5) var numFrames = 2;

or it can be a series of statements grouped together as a statement block:

if (x = = 5) {

var numFrames;

numFrames = 10;

play();

}

As you can see, a statement block is any number of statements on one or more lines,

surrounded by curly braces. Here we show three statements, separated by semi-

colons, all on one line:

{ statement1; statement2; statement3... }

By using a statement block as the substatement of our if statement, we can specify

multiple statements to be executed conditionally (only when the if statement is

true).

This can be very handy.

We can use a statement block anywhere ActionScript expects a single statement. In

fact, statement blocks are sometimes required. For example, the function statement

must always include a statement block, even ...