JavaScript Number Reference

JavaScript Number Reference

JavaScript Numbers

JavaScript has only one type of number.

Numbers can be written with, or without, decimals:


var x = 3.14;     // A number with decimals
var y = 34;       // A number without decimals

Extra large or extra small numbers can be written with scientific (exponent) notation:


var x = 123e5;    // 12300000
var y = 123e-5;   // 0.00123

For a tutorial about JavaScript numbers, read our JavaScript Number Tutorial.

Number Properties

Property Description
constructor Returns the function that created JavaScript's Number prototype
MAX_VALUE Returns the largest number possible in JavaScript
MIN_VALUE Returns the smallest number possible in JavaScript
NEGATIVE_INFINITY Represents negative infinity (returned on overflow)
NaN Represents a "Not-a-Number" value
POSITIVE_INFINITY Represents infinity (returned on overflow)
prototype Allows you to add properties and methods to an object

Number Methods

Method Description
isFinite() Checks whether a value is a finite number
isInteger() Checks whether a value is an integer
isNaN() Checks whether a value is Number.NaN
isSafeInteger() Checks whether a value is a safe integer
toExponential(x) Converts a number into an exponential notation
toFixed(x) Formats a number with x numbers of digits after the decimal point
toPrecision(x) Formats a number to x length
toString() Converts a number to a string
valueOf() Returns the primitive value of a number

All number methods return a new value. They do not change the original variable.