JavaScript Number Reference

JavaScript Numbers

JavaScript has only one type of number.

Numbers can be written with, or without, decimals:

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

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

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

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

Name	Description
constructor	Returns the function that created JavaScript's Number prototype
EPSILON	Returns the difference between 1 and the smallest number greater than 1
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
MAX_SAFE_INTEGER	Returns the maximum safe integer in JavaScript.
MIN_SAFE_INTEGER	Returns the minimum safe integer in JavaScript
MAX_VALUE	Returns the largest number possible in JavaScript
MIN_VALUE	Returns the smallest number possible in JavaScript
NaN	Represents a "Not-a-Number" value
NEGATIVE_INFINITY	Represents negative infinity (returned on overflow)
POSITIVE_INFINITY	Represents infinity (returned on overflow)
parseFloat()	Parses a string an returns a number
parseInt()	Parses a string an returns a whole number
prototype	Allows you to add properties and methods to an object
toExponential(x)	Converts a number into an exponential notation
toFixed(x)	Formats a number with x numbers of digits after the decimal point
toLocaleString()	Converts a number into a string, based on the locale settings
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 value.