ActionScript for Flash MX: The Definitive Guide, Second Edition

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

The Logical Operators

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The Logical Operators

In Chapter 4, we saw how to make logical decisions using conditional expressions

and Boolean values. The decisions were based on single factors: if a movie hasn’t

loaded, don’t start playing; if a spaceship has double-shot power, increase the dam-

age its shots inflict; and so on. Not all programming logic is so simple. We’ll often

want to consider multiple factors in our branching (i.e., decision-making) logic.

Suppose, for example, that we are making a personalized Flash site that requires

users to log in. If a user logs in as a guest, the content he can see is limited. When a

registered user logs into the site, we set a variable that indicates, for the duration of

our movie, that the user is allowed to see privileged content:

var userStatus = "registered";

To decide whether to allow access to a restricted area, we use a Boolean check like

this:

if (userStatus = = "registered") {

// It's okay, let 'em in...

}

Suppose we want to demonstrate the site to prospective investors without forcing

them to register and without showing them material reserved for registered users.

We can invent a new user category, “specialGuest”, that allows investors to see more

than a guest but not as much as a registered user. When we want to identify some-

one as ...