HTML and CSS Reference

In-Depth Information

Using Number Constants and Different Bases.
The constants
MAX_VALUE
,

MIN_VALUE
,
NEGATIVE_INFINITY
,
POSITIVE_INFINITY
, and
NaN
are properties of

the
Number()
function, but are not used with instances of the
Number
object; thus,
var

huge = Number.MAX_VALUE
is valid, but
huge.MAX_VALUE
is not.
NaN
is a special

value that is returned when some mathematical operation results in a value that is not

a number.

The methods provided to the
Number
object manipulate instances of number objects.

For example, to convert numbers to strings representing different bases, the
toString()

method manipulates a number, either primitive or object. See Example 9.31.

EXAMPLE
9.31

<html>

<head><title>Number Contants</title></head>

<body bgcolor="orange"><font color="black" size="+1">

<h2>Constants</h2>

<script type="text/javascript">

1

var largest = Number.MAX_VALUE;

2

var smallest = Number.MIN_VALUE;

3

var num1 = 20;
//
A primitive numeric value

4

var num2 = new Number(13);
//
Creating a Number object

document.write("<b>The largest number is " +
largest

+ "<br />");

document.write("The smallest number is "+
smallest

+ "<br />");

5

document.write("The number as a string (base 2): "+

num1.toString(2)
);

6

document.write("<br />The number as a string (base 8): "+

num2.toString(8)
);

7

document.write("<br />The square root of -25 is: "+

Math.sqrt(-25)
+ "<br />");

</script>

</body>

</html>

EXPLANATION

1

The constant
MAX_VALUE
is a property of the
Number()
function. This constant

cannot be used with an instance of a
Number
object.

2

The constant
MIN_VALUE
is a property of the
Number()
function.

3

A number is assigned to the variable called
num1
.

4

A new
Number
object is created with the
Number()
constructor and assigned to

num2
. It is easier to use the literal notation:
num2 = 13
.

5

The number is converted to a string represented in binary, base 2.

6

The number is converted to a string represented in octal, base 8.

7

The square root of a negative number is illegal. JavaScript returns
NaN
, not a

number, when this calculation is attempted (see Figure 9.36).