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.

Numeric Literals

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}

}

// Round a number to two decimal places

trace(roundNum(1.12645, 2)); // Displays: 1.13

Special Values of the Number Datatype

Integer and floating-point literals account for nearly all the legal values of the num-

ber datatype, but there are special keyword values that represent the following

numeric concepts: Not-a-Number, Minimum Allowed Value, Maximum Allowed

Value, Infinity, and Negative Infinity.

Each of the special values can be assigned to variables and properties or used in lit-

eral expressions, just like any other numeric literal. More often than not, though, the

special numeric values are returned by the interpreter as the result of some expres-

sion evaluation.

Not-a-Number: NaN

Occasionally, a mathematical computation or an attempted datatype conversion

results in a value that simply is not a number. For example, 0/0 is an impossible cal-

culation, and the following expression can’t be converted to a finite number:

23 – "go ahead and try!"

In order to accommodate data that is of the number type but is not a calculable num-

ber, ActionScript provides the

NaN keyword value. Though NaN doesn’t represent a

calculable number, it is still a legal value of the number type, as demonstrated by the

following code:

x = 0/0;

trace(x); // Displays: NaN

trace(typeof x); ...