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JavaScript Tutorial: Numbers and Mathematical Functions

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JavaScript has only one type of number (in contrast to, e.g. Visual Basic, which differentiates between e.g. integers, floating point numbers and double precision numbers). Numbers can be written with or without decimal points and/or with or without (scientific) exponents, e.g.

 

var x = 4.1;    // With a decimal point

var y = 4;      // Without a decimal point

var p = 135e6   // Means 135000000

var q = 13.5e-3 // Means 0.0135

 

Numbers have the following properties and methods:

 

Properties:

 

Property

Description

More

constructor

Returns object’s constructor function

Here

MAX_VALUE

Returns largest (positive) number recognised by the browser’s JavaScript

Here

MIN_VALUE

Returns smallest (positive) number recognised by the browser’s JavaScript

Here

NEGATIVE_INFINITY

Represents negative infinity (i.e. if computation overflows)

Here

NaN

Represents Not-a-Number (i.e. if computation overflows

Here

POSITIVE_INFINITY

Represents positive infinity (i.e. if computation overflows)

Here

prototype

Allows author to add properties and methods to an object

Here

 

Methods:

 

Method

Description

More

isFinite()

Returns true if value is a finite number, otherwise returns false

Here

isInteger()

Returns true if value is of type Number and is an integer (within range understood as integers by the browser), otherwise returns false

Here

isNaN()

Returns true if value is NaN, otherwise returns false

Here

isSafeInteger()

Returns true if value is of type Number and is a safe integer, otherwise false. A safe integer is one that can be exactly represented as an IEEE-754 double precision number, i.e. is an integer in the range -(253 - 1) to (253 - 1).

Here

toExponential()

Returns a string representing the number converted into exponential form. The optional parameter (0 to 20) represents the number of digits retained after the decimal point

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toFixed()

Returns a string representing the number with a fixed number of digits after the decimal point

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toPrecision()

Returns a string representing the number with a fixed number of significant digits

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toString()

Returns a string corresponding to the number

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valueOf()

Returns the primitive value of an object. For a number, this in effect just returns the number itself

Here

 

The Math object

 

Associated with numbers is the JavaScript Math object. This allows authors to carry out some mathematical manipulations. It supports the following properties and methods:

 

Math object properties:

 

Property

Description

More

E

Returns Euler’s constant,

Here

LN2

Returns the natural logarithm of 2

Here

LN10

Returns the natural logarithm of 10

Here

LOG2E

Returns the base-2 logarithm of

Here

LOG10E

Returns the base-10 logarithm of

Here

PI

Returns

Here

SQRT1_2

Returns

Here

SQRT2

Returns

Here

 

Math object methods:

 

Method

Description

More

abs()

Returns the absolute value of a real number

Here

acos()

Returns the (principal) arccosine of a real number

Here

acosh()

Returns the (principal) hyperbolic arccosine of a real number

Here

asin()

Returns the (principal) arcsine of a real number

Here

asinh()

Returns the (principal) hyperbolic arcsine of a real number

Here

atan()

Returns the (principal) arctangent of a real number

Here

atanh()

Returns the (principal) hyperbolic arctangent of a real number

Here

atan2()

Returns the arctangent of the specified x- and y-coordinates

Here

cbrt()

Returns the cube root of a real number

Here

ceil()

Rounds a real number towards positive infinity

Here

cos()

Returns the cosine of a real number

Here

cosh()

Returns the hyperbolic cosine of a real number

Here

exp()

Returns the exponential of a real number (i.e. )

Here

floor()

Rounds a real number towards negative infinity

Here

log()

Returns the natural logarithm of a positive real number

Here

max()

Returns the maximum of a set of real numbers

Here

min()

Returns the minimum of a set of real numbers

Here

pow()

Returns x to the power y. Note, ^ has a different meaning in JavaScript

Here

random()

Returns a (uniform) random number between 0 and 1

Here

round()

Rounds a real number to the nearest integer

Here

sin()

Returns the sine of a real number

Here

sinh()

Returns the hyperbolic sine of a real number

Here

sqrt()

Returns the square root of a real (non-negative) number

Here

tan()

Returns the tangent of a real number

Here

tan()

Returns the hyperbolic tangent of a real number

Here

 


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