The Number Object

As you can guess from its name , the Number object handles numbers. Mostly, there's little need to use this object, because you can just use simple numbers instead, and JavaScript is good at that. In fact, JavaScript creates Number objects from simple numbers automatically as it needs them. It's useful to know the properties and methods of the Number object, however, and you can find them in Table 19.4 in overview, its properties in depth in Table 19.5, and its methods in depth in Table 19.6.

Table 19.4. Overview of the Properties and Methods of the Number Object

Properties	Methods
`constructor`	`toExponential`
`MAX_VALUE`	`toFixed`
`MIN_VALUE`	`toLocaleString`
`NaN`	`toPrecision`
`NEGATIVE_INFINITY`	`toString`
`POSITIVE_INFINITY`	`valueOf`
`Prototype`

Table 19.5. The Properties of the Number Object

Property	NS2	NS3	NS4	NS6	IE3a	IE3b	IE4	IE5	IE5.5	IE6
`constructor`			x	x			x	x	x	x
	Read/write
	This property specifies the function that creates an object.
`MAX_VALUE`		x	x	x		x	x	x	x	x
	Read-only
	This property holds the maximum possible numeric value JavaScript can handle, typically about 1.79E+308.
`MIN_VALUE`		x	x	x		x	x	x	x	x
	Read-only
	This property holds the minimum possible numeric value JavaScript can handle, typically about 5.00E-324.
`NaN`		x	x	x		x	x	x	x	x
	Read-only
	This property, "Not a Number," is a special value that indicates an arithmetic expression returned a value that was not a number.
`NEGATIVE_INFINITY`			x	x	x		x	x	x	x
x
	Read-only
	This property is how JavaScript refers to negative infinity.
`POSITIVE_INFINITY`			x	x	x		x	x	x	x
x
	Read-only
	This property is how JavaScript refers to positive infinity.
`prototype`			x	x			x	x	x	x
	Read/write
	This property returns a reference to the object's prototype. You use the `prototype` property to provide base functionality to a class of objects. See "Using the `prototype` Property" in this chapter.

Table 19.6. The Methods of the Number Object

Method	NS2	NS3	NS4	NS6	IE4	IE5	IE5.5	IE6
`toExponential`				x			x	x
	Returns: String
	This method returns a string containing a number in exponential form.
	Syntax: `number` `.toExponential(` `digits` `)` , where `digits` is the number of digits after the decimal point.
`toFixed`				x			x	x
	Returns: String
	This method returns a string containing the number in fixed-point notation.
	Syntax: `number` `.toFixed(` `digits` `)` , where `digits` is the number of digits after the decimal point.
`toLocaleString`				x			x	x
	Returns: String
	This method returns a number converted to a string using the current locale.
	Syntax: `number` `.toLocaleString()` .
`toPrecision`				x			x	x
	Returns: String
	This method returns a string containing a number in either exponential or fixed-point form with a specified number of digits.
	Syntax: `number` `.toPrecision(` `digits` `)` , where `digits` is the number of significant (total) digits.
`toString`		x	x	x	x	x	x	x
	Returns: String
	This method returns the number as a string.
	Syntax: `number` `.toString()` .
`valueOf`			x	x	x	x	x	x
	Returns: Number
	This method returns the value of the number contained by the `Number` object.
	Syntax: `number` `.valueOf()` .