ActionScript for Flash MX: The Definitive Guide, Second Edition

This is the Title of the Book, eMatter Edition

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

Loop Terminology

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var words = ["Toronto", "is", "not", "the", "capital", "of", "Canada"];

var sentence;

var i = 0;

while (i < words.length) {

sentence += words[i]; // Add the current word to the sentence

// If it's not the last word...

if (i < words.length - 1) {

sentence += " "; // ...tack on a space

} else {

sentence += "."; // ...otherwise, end with a period

}

i++;

}

trace(sentence); // Displays: "Toronto is not the capital of Canada."

Nearly all loops involve some kind of counter (sometimes called an iterator or index

variable). Counters let us cycle sequentially through data. This technique is particu-

larly convenient when we determine the counter’s maximum limit using the

length

property of the array or string we want to manipulate, as we did in the preceding

example.

It’s also possible to create a loop whose end point doesn’t depend on a counter. As

long as the test expression of the loop eventually becomes

false, the loop will end.

Here, for example, we examine the document level stack of the Flash Player to deter-

mine the first vacant level:

var i = 0;

while (typeof eval("_level" + i) = = "movieclip") {

i++;

}

trace("The first vacant level is " + i);

// Now load a movie into the vacant level, knowing it's free

loadMovieNum("myMovie.swf", i);

For more information on document levels, ...