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.

Working with Strings

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105

trace("The first character of msg is a copyright symbol.");

}

You may encounter the deprecated Flash 4 code point functions, ord() and mbord(),

when examining legacy code. The charCodeAt() function should be used in Flash 5

and later.

Executing Code in a String with eval

In ActionScript, the eval() function converts a string to an identifier (i.e., a variable

name). But to thoroughly understand the ActionScript eval() function, you must first

understand how JavaScript’s analogous eval() function works. In JavaScript, eval() is

a built-in function that converts any string to a block of code and then executes that

block of code. The syntax for JavaScript’s eval() is:

eval(string)

When eval() is executed in JavaScript, the interpreter converts string to executable

code, runs that code, and returns the resulting value (if a value is generated). Con-

sider the following JavaScript examples:

eval("parseInt('1.5')"); // Calls the parseInt() function, which returns 1

eval("var x = 5"); // Creates a new variable named x and sets its value to 5

If you’ve never seen eval() before, you may be thinking, “When would I ever have a

string with code in it? Why not just write the code out?” Answer: because eval() lets

you dynamically generate code when you need to. For example,