Number

Number is the built-in object corresponding to the primitive number data type. As discussed in Chapter 3, all numbers are represented in IEEE 754-1985 double-precision floating-point format. This representation is 64 bits long, permitting floating-point magnitudes as large as ±1.7976 10 ³⁰⁸ and as small as ±2.2250 10 ^-308 . The Number() constructor takes an optional argument specifying its initial value:

 var x = new Number(); var y = new Number(17.5); 

Table 7-5 lists the special numeric values that are provided as properties of the Number object.

Table 7-5: Properties of the Number Object

Property	Value
Number.MAX_VALUE	Largest magnitude representable
Number.MIN_VALUE	Smallest magnitude representable
Number.POSITIVE_INFINITY	The special value Infinity
Number.NEGATIVE_INFINITY	The special value -Infinity
Number.NaN	The special value NaN

The only useful method of this object is toString() , which returns the value of the number in a string. Of course it is rarely needed, given that generally a number type converts to a string when we need to use it as such.